funman300
18d7937b51
DrawMode is a fieldless two-variant enum — it is trivially bitwise- copyable. Adding Copy + updating choose_winnable_seed to take the value directly eliminates 13 superfluous .clone() calls across solitaire_core, solitaire_engine, solitaire_assetgen, and solitaire_wasm. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
1248 lines
50 KiB
Rust
1248 lines
50 KiB
Rust
//! Klondike solvability checker.
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//!
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//! Used by the engine to back the **Settings → Gameplay → "Winnable
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//! deals only"** toggle: when on, the engine retries fresh deal seeds
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//! until [`try_solve`] returns [`SolverResult::Winnable`] (or
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//! [`SolverResult::Inconclusive`], which we treat as winnable because
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//! we cannot prove otherwise) up to a fixed retry cap.
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//!
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//! The implementation is a hand-rolled depth-first search with
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//! memoisation on a deterministic canonical state hash. It uses no
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//! external crates beyond what `solitaire_core` already depends on
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//! (`std::collections::HashSet`, `std::hash::DefaultHasher`).
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//!
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//! # Algorithm
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//!
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//! 1. Encode the game state into a canonical `u64` hash. Tableau
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//! columns are encoded top-to-bottom along with each card's face
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//! state; foundations are encoded by their top card; stock and
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//! waste are encoded as the concatenation of their card ids in
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//! order. Two states with the same canonical hash are considered
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//! equivalent for the purposes of pruning.
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//!
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//! 2. At each search step, enumerate the candidate moves in priority
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//! order:
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//! - **Foundation moves first** — moving a card to a foundation
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//! pile reduces the search frontier and never traps the player.
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//! Aces and twos are unconditional (the spec calls these out as
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//! "no choice involved" forced plays).
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//! - **Inter-tableau moves next** — moves between tableau columns
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//! that *don't* immediately undo the previous move (a "self-undo"
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//! filter prevents the trivial A→B then B→A cycle).
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//! - **Stock/waste draw last** — drawing permutes a long sequence
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//! and is the costliest move. It's also the only source of
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//! branching once the tableau is locked, so we enumerate it last
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//! and only when no productive move was made since the previous
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//! stock cycle (we track this with a "drew without other progress"
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//! counter).
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//!
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//! 3. After each move, recurse. If the recursion finds a win we
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//! propagate `Winnable` immediately. If the visited-state set or
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//! the move-budget counter is exhausted we return `Inconclusive`.
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//! Otherwise we exhaust all moves and return `Unwinnable`.
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//!
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//! # Determinism
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//!
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//! The search is fully deterministic: move enumeration walks piles in
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//! a fixed order and the canonical hash is built with `DefaultHasher`,
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//! whose seed is fixed across program runs but documented as not
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//! cryptographically stable. For the purposes of "same input → same
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//! output across one program run" this is sufficient; the spec
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//! explicitly calls `DefaultHasher` "fine for this".
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//!
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//! # Performance
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//!
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//! On real fresh deals the solver completes in tens of milliseconds
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//! (median ~30 ms on the synthetic deals used by the tests below).
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//! Pathological deals are bounded by [`SolverConfig::move_budget`] and
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//! [`SolverConfig::state_budget`] — when either trips we return
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//! [`SolverResult::Inconclusive`]. The retry loop in the engine treats
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//! Inconclusive as winnable so a player who turns the toggle on never
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//! sees a hung "searching..." state.
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use std::collections::HashSet;
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use std::hash::{Hash, Hasher};
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use crate::card::{Card, Suit};
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use crate::deck::{deal_klondike, Deck};
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use crate::game_state::{DrawMode, GameState};
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use crate::pile::{Pile, PileType};
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use crate::rules::{can_place_on_foundation, can_place_on_tableau, is_valid_tableau_sequence};
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/// Verdict returned by [`try_solve`].
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub enum SolverResult {
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/// The solver found a sequence of moves that wins the deal.
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Winnable,
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/// The solver exhaustively searched and confirmed no win exists.
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Unwinnable,
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/// The time / move budget was exceeded before a verdict could be
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/// reached. Callers should treat this as winnable since we cannot
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/// prove otherwise — Klondike has many deals where the search tree
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/// is theoretically tractable but practically too wide for a
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/// bounded DFS.
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Inconclusive,
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}
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/// Tunable budgets controlling how long [`try_solve`] is willing to
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/// search before bailing out with [`SolverResult::Inconclusive`].
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub struct SolverConfig {
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/// Maximum total moves to consider across the entire search tree.
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/// Default: `100_000`. A realistic Klondike solve fits in
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/// ~10k–30k moves for solvable deals; the cap lets us bail out of
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/// pathological states.
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pub move_budget: u64,
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/// Maximum unique states to visit. Memoisation prevents revisiting,
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/// but the visited set grows unbounded without a cap. Default:
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/// `200_000`.
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pub state_budget: usize,
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}
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impl Default for SolverConfig {
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fn default() -> Self {
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Self {
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move_budget: 100_000,
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state_budget: 200_000,
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}
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}
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}
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/// A single move the solver can recommend, expressed in terms of the
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/// engine-level `(source, dest, count)` triple used by `MoveRequestEvent`.
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///
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/// Returned as part of [`SolveOutcome::first_move`] when
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/// [`try_solve_with_first_move`] or [`try_solve_from_state`] proves the
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/// position winnable. The hint system surfaces this to the player as the
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/// "provably best" first move.
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///
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/// `count` is always `1` for non-tableau-to-tableau moves (foundation moves
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/// always move a single card; waste moves a single card; draws use a
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/// dedicated representation that the public API surfaces as
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/// `source: PileType::Stock, dest: PileType::Waste, count: 1`).
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub struct SolverMove {
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/// Pile the move originates from.
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pub source: PileType,
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/// Pile the move lands on.
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pub dest: PileType,
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/// Number of cards in the move (1 for non-tableau-to-tableau moves).
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pub count: usize,
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}
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/// Solver verdict plus, when winnable, the first move on a winning path.
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///
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/// `result == Winnable` guarantees `first_move == Some(_)`; the inverse
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/// holds only when the search proved a verdict — `Inconclusive` and
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/// `Unwinnable` always carry `first_move == None`.
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub struct SolveOutcome {
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/// The high-level verdict (Winnable / Unwinnable / Inconclusive).
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pub result: SolverResult,
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/// First move on the solution path when `result == Winnable`,
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/// otherwise `None`.
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pub first_move: Option<SolverMove>,
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}
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/// Tries to solve a fresh Classic-mode game from `seed` + `draw_mode`.
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///
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/// This is a pure function — same input always yields the same
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/// [`SolverResult`] within one program run.
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///
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/// The solver only explores *Classic* Klondike rules: there's no
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/// undo, no Zen-mode score suppression, and no Challenge-mode undo
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/// ban (irrelevant since the solver never undoes). The same engine
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/// rules ([`can_place_on_foundation`], [`can_place_on_tableau`],
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/// [`is_valid_tableau_sequence`]) drive move enumeration so the
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/// solver's notion of "legal" exactly matches the live game.
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pub fn try_solve(seed: u64, draw_mode: DrawMode, config: &SolverConfig) -> SolverResult {
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// Delegate to the path-recording variant and discard the move. The path
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// recording is cheap (a single Option<SolverMove> per stack frame) so
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// this preserves `try_solve`'s existing performance characteristics —
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// the new-game retry loop, which is the hot caller, sees no slowdown.
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try_solve_with_first_move(seed, draw_mode, config).result
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}
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/// Tries to solve a fresh Classic-mode game from `seed` + `draw_mode` and,
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/// when a win is found, returns the first move on the winning path.
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///
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/// Same semantics as [`try_solve`] for the verdict; the only difference is
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/// that the [`SolveOutcome::first_move`] is populated when `result ==
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/// SolverResult::Winnable`. `Unwinnable` and `Inconclusive` always carry
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/// `first_move == None`.
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///
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/// Used by the engine hint system to promote H-key suggestions from a
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/// heuristic to the provably-optimal first move; the hint system falls
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/// back to its heuristic when this returns `Inconclusive`.
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pub fn try_solve_with_first_move(
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seed: u64,
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draw_mode: DrawMode,
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config: &SolverConfig,
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) -> SolveOutcome {
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let state = SolverState::initial(seed, draw_mode);
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state.solve(config)
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}
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/// Tries to solve from an existing in-progress [`GameState`].
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///
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/// Mirrors [`try_solve_with_first_move`] but takes a live `GameState`
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/// instead of a fresh seed. The hint system uses this so it can ask the
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/// solver about the actual board the player is staring at, not just the
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/// initial deal.
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///
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/// Reads `state.draw_mode` and the current pile contents. The active
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/// `GameMode` is irrelevant — the solver only models Classic Klondike
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/// rules, which are a strict subset of every other mode (Zen / Challenge
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/// only differ in scoring and undo-availability).
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pub fn try_solve_from_state(state: &GameState, config: &SolverConfig) -> SolveOutcome {
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let solver_state = SolverState::from_game_state(state);
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solver_state.solve(config)
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}
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// ---------------------------------------------------------------------------
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// Internal solver state
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// ---------------------------------------------------------------------------
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/// The candidate moves the solver enumerates at each step. Distinct
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/// from `MoveRequestEvent` (engine-level) and `move_cards` (game-level)
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/// because the solver also needs to model the stock-draw + recycle as a
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/// first-class move. Distinct from the public [`SolverMove`] because the
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/// internal form encodes each move kind structurally for fast pattern
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/// matching during enumeration.
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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enum InternalMove {
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/// Move `count` cards from a tableau column to another tableau column.
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TableauToTableau { from: usize, to: usize, count: usize },
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/// Move the top of a tableau column to a foundation slot.
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TableauToFoundation { from: usize, slot: u8 },
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/// Move the top of the waste pile to a tableau column.
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WasteToTableau { to: usize },
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/// Move the top of the waste pile to a foundation slot.
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WasteToFoundation { slot: u8 },
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/// Draw from stock to waste (or recycle waste → stock if stock is empty).
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Draw,
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}
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impl InternalMove {
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/// Convert this internal move into the public [`SolverMove`] form
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/// suitable for handing off to the engine layer. Cheap — `O(1)` field
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/// rewrites with no allocation.
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fn to_public(self) -> SolverMove {
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match self {
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InternalMove::TableauToTableau { from, to, count } => SolverMove {
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source: PileType::Tableau(from),
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dest: PileType::Tableau(to),
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count,
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},
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InternalMove::TableauToFoundation { from, slot } => SolverMove {
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source: PileType::Tableau(from),
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dest: PileType::Foundation(slot),
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count: 1,
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},
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InternalMove::WasteToTableau { to } => SolverMove {
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source: PileType::Waste,
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dest: PileType::Tableau(to),
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count: 1,
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},
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InternalMove::WasteToFoundation { slot } => SolverMove {
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source: PileType::Waste,
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dest: PileType::Foundation(slot),
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count: 1,
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},
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InternalMove::Draw => SolverMove {
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source: PileType::Stock,
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dest: PileType::Waste,
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count: 1,
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},
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}
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}
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}
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/// Compact replica of `GameState` tailored for the solver. Strips
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/// undo / score / move-count tracking and replaces the `HashMap` of
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/// piles with fixed arrays so the canonical hash is cheap to compute.
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#[derive(Clone)]
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struct SolverState {
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tableau: [Vec<Card>; 7],
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foundation: [Vec<Card>; 4],
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stock: Vec<Card>,
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waste: Vec<Card>,
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draw_mode: DrawMode,
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/// True when we just drew (or recycled) and have not yet made a
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/// productive non-draw move. While set, further consecutive draws
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/// without intervening progress are skipped — see the algorithm
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/// note above.
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just_drew: bool,
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/// Number of draws performed since the last non-draw move. Used
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/// to detect "we've cycled the entire stock without finding any
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/// playable card", which guarantees no further benefit from
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/// drawing.
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consecutive_draws: u32,
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}
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impl SolverState {
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fn initial(seed: u64, draw_mode: DrawMode) -> Self {
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let mut deck = Deck::new();
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deck.shuffle(seed);
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let (tableau_piles, stock_pile) = deal_klondike(deck);
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let tableau: [Vec<Card>; 7] = tableau_piles.map(|p| p.cards);
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let foundation: [Vec<Card>; 4] = core::array::from_fn(|_| Vec::new());
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Self {
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tableau,
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foundation,
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stock: stock_pile.cards,
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waste: Vec::new(),
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draw_mode,
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just_drew: false,
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consecutive_draws: 0,
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}
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}
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/// True when every foundation slot has 13 cards.
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fn is_won(&self) -> bool {
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self.foundation.iter().all(|f| f.len() == 13)
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}
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/// Returns the foundation slot that already claims `suit`, or the
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/// first empty slot if no slot claims it. Used so foundation moves
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/// always target a single deterministic slot per (card, board) pair.
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fn target_foundation_slot(&self, suit: Suit) -> Option<u8> {
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let mut empty: Option<u8> = None;
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for (idx, pile) in self.foundation.iter().enumerate() {
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match pile.first() {
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Some(bottom) if bottom.suit == suit => return Some(idx as u8),
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None if empty.is_none() => empty = Some(idx as u8),
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_ => {}
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}
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}
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empty
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}
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/// Build a temporary `Pile` view for use with the rule helpers.
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/// Cheap clone — the helpers only inspect the top card, so we
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/// pass a thin wrapper. (The compiler reuses the inner Vec by
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/// value because we drop it immediately.)
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fn pile_view(pile_type: PileType, cards: &[Card]) -> Pile {
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Pile {
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pile_type,
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cards: cards.to_vec(),
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}
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}
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/// Enumerate every legal candidate move in priority order:
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/// foundation > inter-tableau > waste-to-tableau > stock-draw.
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/// The order matters — foundation moves shrink the search frontier
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/// fastest, and stock-draws are the costliest. See the top-of-file
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/// algorithm note.
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fn enumerate_moves(&self) -> Vec<InternalMove> {
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let mut moves: Vec<InternalMove> = Vec::new();
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// 1) Foundation moves from tableau tops.
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for (i, col) in self.tableau.iter().enumerate() {
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if let Some(top) = col.last()
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&& top.face_up
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&& let Some(slot) = self.target_foundation_slot(top.suit)
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{
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let foundation_pile = Self::pile_view(
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PileType::Foundation(slot),
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&self.foundation[slot as usize],
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);
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if can_place_on_foundation(top, &foundation_pile) {
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moves.push(InternalMove::TableauToFoundation { from: i, slot });
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}
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}
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}
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// 2) Foundation move from the waste top.
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if let Some(top) = self.waste.last()
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&& let Some(slot) = self.target_foundation_slot(top.suit)
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{
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let foundation_pile = Self::pile_view(
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PileType::Foundation(slot),
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&self.foundation[slot as usize],
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);
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if can_place_on_foundation(top, &foundation_pile) {
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moves.push(InternalMove::WasteToFoundation { slot });
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}
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}
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// 3) Inter-tableau moves. For each source column, find the
|
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// longest face-up valid run, then enumerate every prefix
|
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// length that lands legally on every other column. Skip
|
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// moves that just relocate a King onto an empty column when
|
||
// the source column would also be left empty (a no-op).
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for src in 0..7usize {
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let col = &self.tableau[src];
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if col.is_empty() {
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continue;
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}
|
||
// Find the largest k such that col[col.len()-k..] is all
|
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// face-up and a valid descending alternating run.
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let max_run = longest_face_up_run(col);
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for count in 1..=max_run {
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let start = col.len() - count;
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let bottom = &col[start];
|
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for dst in 0..7usize {
|
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if dst == src {
|
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continue;
|
||
}
|
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let dst_pile = Self::pile_view(PileType::Tableau(dst), &self.tableau[dst]);
|
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if !can_place_on_tableau(bottom, &dst_pile) {
|
||
continue;
|
||
}
|
||
// Prune the no-op "drag a King from an empty-after-move
|
||
// column onto another empty column".
|
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let leaves_source_empty = start == 0;
|
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let dest_empty = self.tableau[dst].is_empty();
|
||
if leaves_source_empty
|
||
&& dest_empty
|
||
&& bottom.rank == crate::card::Rank::King
|
||
{
|
||
continue;
|
||
}
|
||
moves.push(InternalMove::TableauToTableau { from: src, to: dst, count });
|
||
}
|
||
}
|
||
}
|
||
|
||
// 4) Waste → tableau.
|
||
if let Some(top) = self.waste.last() {
|
||
for dst in 0..7usize {
|
||
let dst_pile = Self::pile_view(PileType::Tableau(dst), &self.tableau[dst]);
|
||
if can_place_on_tableau(top, &dst_pile) {
|
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moves.push(InternalMove::WasteToTableau { to: dst });
|
||
}
|
||
}
|
||
}
|
||
|
||
// 5) Draw — but only if there's something to draw or recycle.
|
||
// Skip draws when we've already cycled the full stock+waste
|
||
// once without making progress; the deterministic stock
|
||
// permutation can't produce new value at that point.
|
||
let can_draw = !self.stock.is_empty() || !self.waste.is_empty();
|
||
let stock_cycle_len = (self.stock.len() + self.waste.len()) as u32;
|
||
// `consecutive_draws > stock_cycle_len` is a conservative cap:
|
||
// a single full cycle requires at most `ceil(stock_cycle_len / draw_count)`
|
||
// draws (Draw 1 → exactly stock_cycle_len; Draw 3 → fewer), so
|
||
// anything past that without intervening progress is wasteful.
|
||
let cycled_without_progress =
|
||
self.consecutive_draws > stock_cycle_len.saturating_add(1);
|
||
if can_draw && !cycled_without_progress {
|
||
moves.push(InternalMove::Draw);
|
||
}
|
||
|
||
moves
|
||
}
|
||
|
||
/// Apply `mv` to `self`, returning the previous `consecutive_draws`
|
||
/// value so the caller can restore it on backtrack.
|
||
fn apply_move(&mut self, mv: InternalMove) -> SolverStateUndo {
|
||
let prev_just_drew = self.just_drew;
|
||
let prev_consec = self.consecutive_draws;
|
||
match mv {
|
||
InternalMove::TableauToTableau { from, to, count } => {
|
||
let start = self.tableau[from].len() - count;
|
||
let moved: Vec<Card> = self.tableau[from].split_off(start);
|
||
self.tableau[to].extend(moved);
|
||
// Flip the newly exposed source top.
|
||
if let Some(top) = self.tableau[from].last_mut()
|
||
&& !top.face_up
|
||
{
|
||
top.face_up = true;
|
||
}
|
||
self.just_drew = false;
|
||
self.consecutive_draws = 0;
|
||
}
|
||
InternalMove::TableauToFoundation { from, slot } => {
|
||
if let Some(card) = self.tableau[from].pop() {
|
||
self.foundation[slot as usize].push(card);
|
||
if let Some(top) = self.tableau[from].last_mut()
|
||
&& !top.face_up
|
||
{
|
||
top.face_up = true;
|
||
}
|
||
}
|
||
self.just_drew = false;
|
||
self.consecutive_draws = 0;
|
||
}
|
||
InternalMove::WasteToTableau { to } => {
|
||
if let Some(card) = self.waste.pop() {
|
||
self.tableau[to].push(card);
|
||
}
|
||
self.just_drew = false;
|
||
self.consecutive_draws = 0;
|
||
}
|
||
InternalMove::WasteToFoundation { slot } => {
|
||
if let Some(card) = self.waste.pop() {
|
||
self.foundation[slot as usize].push(card);
|
||
}
|
||
self.just_drew = false;
|
||
self.consecutive_draws = 0;
|
||
}
|
||
InternalMove::Draw => {
|
||
if self.stock.is_empty() {
|
||
// Recycle waste back to stock face-down, reversed.
|
||
let mut recycled: Vec<Card> = self.waste.drain(..).collect();
|
||
recycled.reverse();
|
||
for mut c in recycled {
|
||
c.face_up = false;
|
||
self.stock.push(c);
|
||
}
|
||
} else {
|
||
let draw_count = match self.draw_mode {
|
||
DrawMode::DrawOne => 1,
|
||
DrawMode::DrawThree => 3,
|
||
};
|
||
let avail = self.stock.len().min(draw_count);
|
||
let drain_start = self.stock.len() - avail;
|
||
let drawn: Vec<Card> = self.stock.drain(drain_start..).collect();
|
||
for mut c in drawn {
|
||
c.face_up = true;
|
||
self.waste.push(c);
|
||
}
|
||
}
|
||
self.just_drew = true;
|
||
self.consecutive_draws = self.consecutive_draws.saturating_add(1);
|
||
}
|
||
}
|
||
SolverStateUndo {
|
||
prev_just_drew,
|
||
prev_consec,
|
||
}
|
||
}
|
||
|
||
/// Iterative depth-first search using an explicit stack — recursion
|
||
/// blew through Rust's default 8 MB stack on long real-deal solves
|
||
/// because each frame held a `SolverState` clone. The explicit
|
||
/// stack lives on the heap and grows only with `Vec` capacity, not
|
||
/// with thread-stack pages.
|
||
///
|
||
/// Returns `Some(first_move)` (the move applied at the root that led
|
||
/// to a winning leaf) as soon as a winning leaf is found. Returns
|
||
/// `None` if the search exhausts (Unwinnable) or a budget trips —
|
||
/// callers distinguish those two cases via `*budget_exceeded`.
|
||
///
|
||
/// Path recording is implemented by stashing the root-level move on
|
||
/// each pushed frame and propagating it unchanged into deeper
|
||
/// children. Cost: one `Option<InternalMove>` (≤ 16 bytes) per
|
||
/// frame and one branch on push. Negligible on the hot path; the
|
||
/// new-game retry loop sees no measurable slowdown.
|
||
fn search(
|
||
self,
|
||
config: &SolverConfig,
|
||
visited: &mut HashSet<u64>,
|
||
moves_consumed: &mut u64,
|
||
budget_exceeded: &mut bool,
|
||
) -> Option<SolverMove> {
|
||
// Each stack frame keeps a state plus the move iterator we
|
||
// haven't yet expanded. Popping a frame is the backtrack.
|
||
struct Frame {
|
||
state: SolverState,
|
||
pending: std::vec::IntoIter<InternalMove>,
|
||
/// First move on the path from the root to this frame's
|
||
/// state. `None` for the root frame; populated when a child
|
||
/// frame is pushed. Propagates unchanged from parent to deeper
|
||
/// children so any winning leaf can read it directly.
|
||
root_move: Option<InternalMove>,
|
||
}
|
||
// Quick exits before allocating the stack. An already-won state
|
||
// surfaces as Winnable with no move to recommend (the player has
|
||
// nothing left to do); the engine treats this gracefully —
|
||
// `is_won` callers gate H-key hints on `!is_won` already.
|
||
if self.is_won() {
|
||
return None;
|
||
}
|
||
if *moves_consumed >= config.move_budget || visited.len() >= config.state_budget {
|
||
*budget_exceeded = true;
|
||
return None;
|
||
}
|
||
let root_hash = self.canonical_hash();
|
||
if !visited.insert(root_hash) {
|
||
return None;
|
||
}
|
||
let root_moves = self.enumerate_moves();
|
||
let mut stack: Vec<Frame> = Vec::new();
|
||
stack.push(Frame {
|
||
state: self,
|
||
pending: root_moves.into_iter(),
|
||
root_move: None,
|
||
});
|
||
|
||
while let Some(frame) = stack.last_mut() {
|
||
// Budget gates — checked before consuming the next move so
|
||
// the budget exhaustion is reflected in the verdict.
|
||
if *moves_consumed >= config.move_budget
|
||
|| visited.len() >= config.state_budget
|
||
{
|
||
*budget_exceeded = true;
|
||
return None;
|
||
}
|
||
let Some(mv) = frame.pending.next() else {
|
||
// Exhausted this frame's children — backtrack.
|
||
stack.pop();
|
||
continue;
|
||
};
|
||
*moves_consumed = moves_consumed.saturating_add(1);
|
||
// Determine the root-level move for the *child* we are about
|
||
// to push: if the current frame is the root (root_move is
|
||
// None) then the child's root move is `mv` itself; otherwise
|
||
// it inherits from the parent.
|
||
let child_root_move = frame.root_move.unwrap_or(mv);
|
||
let mut next = frame.state.clone();
|
||
next.apply_move(mv);
|
||
if next.is_won() {
|
||
return Some(child_root_move.to_public());
|
||
}
|
||
let h = next.canonical_hash();
|
||
if !visited.insert(h) {
|
||
continue;
|
||
}
|
||
let next_moves = next.enumerate_moves();
|
||
stack.push(Frame {
|
||
state: next,
|
||
pending: next_moves.into_iter(),
|
||
root_move: Some(child_root_move),
|
||
});
|
||
}
|
||
None
|
||
}
|
||
|
||
/// Drive [`SolverState::search`] and convert the raw outcome into a
|
||
/// public [`SolveOutcome`]. Shared by [`try_solve_with_first_move`]
|
||
/// and [`try_solve_from_state`].
|
||
fn solve(self, config: &SolverConfig) -> SolveOutcome {
|
||
let mut visited: HashSet<u64> = HashSet::new();
|
||
let mut moves_consumed: u64 = 0;
|
||
let mut budget_exceeded = false;
|
||
let already_won = self.is_won();
|
||
let first_move = self.search(config, &mut visited, &mut moves_consumed, &mut budget_exceeded);
|
||
let result = if already_won || first_move.is_some() {
|
||
SolverResult::Winnable
|
||
} else if budget_exceeded {
|
||
SolverResult::Inconclusive
|
||
} else {
|
||
SolverResult::Unwinnable
|
||
};
|
||
SolveOutcome { result, first_move }
|
||
}
|
||
|
||
/// Build a `SolverState` from an in-progress [`GameState`].
|
||
///
|
||
/// Reads the live pile contents and `draw_mode`. Missing piles are
|
||
/// treated as empty — the engine's `GameState::new` always populates
|
||
/// every pile slot, but defensive code keeps this loader safe in the
|
||
/// face of partially-constructed test fixtures.
|
||
///
|
||
/// The search-metadata fields (`just_drew`, `consecutive_draws`)
|
||
/// reset to "no draws yet" — the solver is concerned with future
|
||
/// reachability from this position, not the engine's own draw
|
||
/// history.
|
||
fn from_game_state(game: &GameState) -> Self {
|
||
let tableau: [Vec<Card>; 7] = core::array::from_fn(|i| {
|
||
game.piles
|
||
.get(&PileType::Tableau(i))
|
||
.map(|p| p.cards.clone())
|
||
.unwrap_or_default()
|
||
});
|
||
let foundation: [Vec<Card>; 4] = core::array::from_fn(|i| {
|
||
game.piles
|
||
.get(&PileType::Foundation(i as u8))
|
||
.map(|p| p.cards.clone())
|
||
.unwrap_or_default()
|
||
});
|
||
let stock = game
|
||
.piles
|
||
.get(&PileType::Stock)
|
||
.map(|p| p.cards.clone())
|
||
.unwrap_or_default();
|
||
let waste = game
|
||
.piles
|
||
.get(&PileType::Waste)
|
||
.map(|p| p.cards.clone())
|
||
.unwrap_or_default();
|
||
Self {
|
||
tableau,
|
||
foundation,
|
||
stock,
|
||
waste,
|
||
draw_mode: game.draw_mode,
|
||
just_drew: false,
|
||
consecutive_draws: 0,
|
||
}
|
||
}
|
||
|
||
/// Build a deterministic 64-bit hash of the visible game state.
|
||
///
|
||
/// The encoding covers every field that can affect future legal
|
||
/// moves: tableau column contents (with face_up state), foundation
|
||
/// tops (it's enough to know the top card per slot — the rest is
|
||
/// implied by the rank), stock + waste card ids in order, and the
|
||
/// draw mode. Two states that differ only in `just_drew` or
|
||
/// `consecutive_draws` hash equally — those fields are search
|
||
/// metadata, not game state.
|
||
fn canonical_hash(&self) -> u64 {
|
||
let mut h = std::collections::hash_map::DefaultHasher::new();
|
||
// Tag the encoding with a version byte so future schema
|
||
// changes invalidate cached hashes cleanly.
|
||
0u8.hash(&mut h);
|
||
for col in &self.tableau {
|
||
(col.len() as u32).hash(&mut h);
|
||
for c in col {
|
||
c.id.hash(&mut h);
|
||
c.face_up.hash(&mut h);
|
||
}
|
||
}
|
||
for f in &self.foundation {
|
||
match f.last() {
|
||
Some(top) => {
|
||
1u8.hash(&mut h);
|
||
top.id.hash(&mut h);
|
||
}
|
||
None => {
|
||
0u8.hash(&mut h);
|
||
}
|
||
}
|
||
}
|
||
(self.stock.len() as u32).hash(&mut h);
|
||
for c in &self.stock {
|
||
c.id.hash(&mut h);
|
||
}
|
||
(self.waste.len() as u32).hash(&mut h);
|
||
for c in &self.waste {
|
||
c.id.hash(&mut h);
|
||
}
|
||
match self.draw_mode {
|
||
DrawMode::DrawOne => 1u8.hash(&mut h),
|
||
DrawMode::DrawThree => 3u8.hash(&mut h),
|
||
}
|
||
h.finish()
|
||
}
|
||
}
|
||
|
||
/// Bookkeeping captured by [`SolverState::apply_move`] so the caller
|
||
/// could in principle restore mutated state. Currently unused —
|
||
/// `search` clones before applying — but kept so a future iteration
|
||
/// can switch to in-place mutation without changing the apply path.
|
||
#[allow(dead_code)]
|
||
struct SolverStateUndo {
|
||
prev_just_drew: bool,
|
||
prev_consec: u32,
|
||
}
|
||
|
||
/// Returns the length of the longest face-up valid descending
|
||
/// alternating-colour run anchored at the top of `cards`. Returns 0
|
||
/// when the top is face-down (or the column is empty); returns 1 for
|
||
/// a single face-up card; otherwise extends as long as the
|
||
/// `is_valid_tableau_sequence` constraint holds.
|
||
fn longest_face_up_run(cards: &[Card]) -> usize {
|
||
if cards.is_empty() {
|
||
return 0;
|
||
}
|
||
let n = cards.len();
|
||
let mut k = 0usize;
|
||
while k < n {
|
||
let candidate = &cards[n - k - 1..];
|
||
if !candidate.iter().all(|c| c.face_up) {
|
||
break;
|
||
}
|
||
if !is_valid_tableau_sequence(candidate) {
|
||
break;
|
||
}
|
||
k += 1;
|
||
}
|
||
k
|
||
}
|
||
|
||
// ---------------------------------------------------------------------------
|
||
// Tests
|
||
// ---------------------------------------------------------------------------
|
||
|
||
#[cfg(test)]
|
||
mod tests {
|
||
use super::*;
|
||
use crate::card::{Card, Rank, Suit};
|
||
|
||
/// Construct a `SolverState` from raw piles for the synthetic
|
||
/// hand-crafted test scenarios. Skips deck-shuffle and the deal
|
||
/// step so tests can describe a near-finished or pathological
|
||
/// position directly.
|
||
fn synthetic(
|
||
tableau: [Vec<Card>; 7],
|
||
foundation: [Vec<Card>; 4],
|
||
stock: Vec<Card>,
|
||
waste: Vec<Card>,
|
||
draw_mode: DrawMode,
|
||
) -> SolverState {
|
||
SolverState {
|
||
tableau,
|
||
foundation,
|
||
stock,
|
||
waste,
|
||
draw_mode,
|
||
just_drew: false,
|
||
consecutive_draws: 0,
|
||
}
|
||
}
|
||
|
||
fn empty_columns() -> [Vec<Card>; 7] {
|
||
core::array::from_fn(|_| Vec::new())
|
||
}
|
||
|
||
fn empty_foundations() -> [Vec<Card>; 4] {
|
||
core::array::from_fn(|_| Vec::new())
|
||
}
|
||
|
||
fn ace(suit: Suit, id: u32) -> Card {
|
||
Card { id, suit, rank: Rank::Ace, face_up: true }
|
||
}
|
||
|
||
fn rank_card(suit: Suit, rank: Rank, id: u32) -> Card {
|
||
Card { id, suit, rank, face_up: true }
|
||
}
|
||
|
||
fn full_run(suit: Suit, base_id: u32) -> Vec<Card> {
|
||
let ranks = [
|
||
Rank::Ace, Rank::Two, Rank::Three, Rank::Four, Rank::Five,
|
||
Rank::Six, Rank::Seven, Rank::Eight, Rank::Nine, Rank::Ten,
|
||
Rank::Jack, Rank::Queen, Rank::King,
|
||
];
|
||
ranks
|
||
.iter()
|
||
.enumerate()
|
||
.map(|(i, r)| Card {
|
||
id: base_id + i as u32,
|
||
suit,
|
||
rank: *r,
|
||
face_up: true,
|
||
})
|
||
.collect()
|
||
}
|
||
|
||
#[test]
|
||
fn solver_recognises_obviously_winnable_deal() {
|
||
// Construct a position where the four foundations are already
|
||
// 12 cards each (Ace through Queen) and the four Kings sit
|
||
// exposed on individual tableau columns. The solver only has
|
||
// to play the four Kings to win.
|
||
let mut foundations: [Vec<Card>; 4] = empty_foundations();
|
||
for (slot, suit) in [Suit::Clubs, Suit::Diamonds, Suit::Hearts, Suit::Spades]
|
||
.iter()
|
||
.enumerate()
|
||
{
|
||
let mut full = full_run(*suit, (slot as u32) * 13);
|
||
full.pop(); // remove King
|
||
foundations[slot] = full;
|
||
}
|
||
let mut tableau = empty_columns();
|
||
tableau[0] = vec![rank_card(Suit::Clubs, Rank::King, 100)];
|
||
tableau[1] = vec![rank_card(Suit::Diamonds, Rank::King, 101)];
|
||
tableau[2] = vec![rank_card(Suit::Hearts, Rank::King, 102)];
|
||
tableau[3] = vec![rank_card(Suit::Spades, Rank::King, 103)];
|
||
|
||
let state = synthetic(tableau, foundations, Vec::new(), Vec::new(), DrawMode::DrawOne);
|
||
let mut visited: HashSet<u64> = HashSet::new();
|
||
let mut moves_consumed: u64 = 0;
|
||
let mut budget_exceeded = false;
|
||
let cfg = SolverConfig::default();
|
||
let first_move = state.search(&cfg, &mut visited, &mut moves_consumed, &mut budget_exceeded);
|
||
|
||
assert!(first_move.is_some(), "obviously-winnable position must be recognised as Winnable");
|
||
assert!(!budget_exceeded);
|
||
assert!(
|
||
moves_consumed < 1000,
|
||
"near-finished deal should solve in well under 1k moves; consumed {moves_consumed}"
|
||
);
|
||
}
|
||
|
||
#[test]
|
||
fn solver_recognises_obviously_unwinnable_deal() {
|
||
// Synthesise a state where one tableau column buries the Ace
|
||
// of Spades under the Two of Spades, both face-up, with no
|
||
// stock, no waste, no other moves available. The Two cannot
|
||
// go anywhere (nothing to land on; no foundation accepts a
|
||
// bare Two), and the Ace is buried, so the deal is dead.
|
||
let mut tableau = empty_columns();
|
||
// Column 0: bottom-to-top [A♠, 2♠]. The Ace is the bottom
|
||
// card; the Two on top of it has no valid destination.
|
||
tableau[0] = vec![
|
||
Card { id: 0, suit: Suit::Spades, rank: Rank::Ace, face_up: true },
|
||
Card { id: 1, suit: Suit::Spades, rank: Rank::Two, face_up: true },
|
||
];
|
||
// Other six columns isolated. Put a face-up King with no
|
||
// matching Queen anywhere — it cannot move because every
|
||
// other column is empty (Kings move to empty columns, but a
|
||
// King already sitting alone on a column moving to an empty
|
||
// column is a no-op, pruned by enumerate_moves).
|
||
tableau[1] = vec![rank_card(Suit::Clubs, Rank::King, 2)];
|
||
// Empty columns 2..6 — irrelevant.
|
||
|
||
let state = synthetic(
|
||
tableau,
|
||
empty_foundations(),
|
||
Vec::new(),
|
||
Vec::new(),
|
||
DrawMode::DrawOne,
|
||
);
|
||
let cfg = SolverConfig::default();
|
||
let mut visited: HashSet<u64> = HashSet::new();
|
||
let mut moves_consumed: u64 = 0;
|
||
let mut budget_exceeded = false;
|
||
let first_move = state.search(&cfg, &mut visited, &mut moves_consumed, &mut budget_exceeded);
|
||
assert!(first_move.is_none(), "buried Ace under same-suit Two with no recovery must not solve");
|
||
assert!(!budget_exceeded, "small synthetic state must complete within budget");
|
||
}
|
||
|
||
#[test]
|
||
fn solver_returns_inconclusive_when_budget_exceeded() {
|
||
// Tiny budgets force the search to bail before exploring
|
||
// meaningful branches on a real fresh deal.
|
||
let cfg = SolverConfig {
|
||
move_budget: 50,
|
||
state_budget: 50,
|
||
};
|
||
let result = try_solve(0, DrawMode::DrawOne, &cfg);
|
||
assert_eq!(
|
||
result,
|
||
SolverResult::Inconclusive,
|
||
"very tight budgets must surface as Inconclusive on a real deal"
|
||
);
|
||
}
|
||
|
||
#[test]
|
||
fn solver_is_deterministic() {
|
||
// Same seed + same draw mode + same config must always return
|
||
// the same verdict. We use a tight budget so the test runs
|
||
// fast even when seed N happens to be a long-search deal.
|
||
let cfg = SolverConfig {
|
||
move_budget: 5_000,
|
||
state_budget: 5_000,
|
||
};
|
||
let r1 = try_solve(7, DrawMode::DrawOne, &cfg);
|
||
let r2 = try_solve(7, DrawMode::DrawOne, &cfg);
|
||
let r3 = try_solve(7, DrawMode::DrawOne, &cfg);
|
||
assert_eq!(r1, r2, "repeat solves must yield the same result");
|
||
assert_eq!(r2, r3);
|
||
}
|
||
|
||
#[test]
|
||
fn solver_handles_draw_three_mode() {
|
||
// The solver must accept DrawMode::DrawThree and never panic.
|
||
// A tight budget keeps the test fast — we only assert that
|
||
// the call returns a verdict (any of the three variants) and
|
||
// that the verdict is reproducible.
|
||
let cfg = SolverConfig {
|
||
move_budget: 5_000,
|
||
state_budget: 5_000,
|
||
};
|
||
let r1 = try_solve(123, DrawMode::DrawThree, &cfg);
|
||
let r2 = try_solve(123, DrawMode::DrawThree, &cfg);
|
||
assert_eq!(r1, r2, "DrawThree solver must be deterministic");
|
||
}
|
||
|
||
#[test]
|
||
fn try_solve_winnable_synthetic_via_real_init_path() {
|
||
// Cross-check: try_solve with the default budget on a real
|
||
// dealt seed should never panic and should return one of the
|
||
// three verdict variants. We don't pin a specific verdict —
|
||
// that would tightly couple the test to RNG behaviour — but
|
||
// we do assert the function reaches a result.
|
||
let cfg = SolverConfig::default();
|
||
let _verdict = try_solve(42, DrawMode::DrawOne, &cfg);
|
||
// Reaching here means the function returned without panic.
|
||
}
|
||
|
||
#[test]
|
||
fn longest_face_up_run_handles_face_down_at_top() {
|
||
let cards = vec![
|
||
Card { id: 1, suit: Suit::Spades, rank: Rank::King, face_up: false },
|
||
];
|
||
assert_eq!(longest_face_up_run(&cards), 0);
|
||
}
|
||
|
||
#[test]
|
||
fn longest_face_up_run_extends_through_valid_run() {
|
||
let cards = vec![
|
||
// bottom: face-down filler
|
||
Card { id: 0, suit: Suit::Spades, rank: Rank::Two, face_up: false },
|
||
Card { id: 1, suit: Suit::Spades, rank: Rank::King, face_up: true },
|
||
Card { id: 2, suit: Suit::Hearts, rank: Rank::Queen, face_up: true },
|
||
Card { id: 3, suit: Suit::Clubs, rank: Rank::Jack, face_up: true },
|
||
];
|
||
assert_eq!(longest_face_up_run(&cards), 3);
|
||
}
|
||
|
||
#[test]
|
||
fn longest_face_up_run_breaks_on_invalid_sequence() {
|
||
// K♠ Q♥ Q♣ — second pair fails the descending check, so the
|
||
// run is just the top single card (Q♣).
|
||
let cards = vec![
|
||
Card { id: 1, suit: Suit::Spades, rank: Rank::King, face_up: true },
|
||
Card { id: 2, suit: Suit::Hearts, rank: Rank::Queen, face_up: true },
|
||
Card { id: 3, suit: Suit::Clubs, rank: Rank::Queen, face_up: true },
|
||
];
|
||
assert_eq!(longest_face_up_run(&cards), 1);
|
||
}
|
||
|
||
#[test]
|
||
fn target_foundation_slot_prefers_claimed_suit() {
|
||
let mut state = synthetic(
|
||
empty_columns(),
|
||
empty_foundations(),
|
||
Vec::new(),
|
||
Vec::new(),
|
||
DrawMode::DrawOne,
|
||
);
|
||
// Slot 0 is empty; slot 1 already holds the Ace of Hearts.
|
||
state.foundation[1].push(ace(Suit::Hearts, 0));
|
||
assert_eq!(state.target_foundation_slot(Suit::Hearts), Some(1));
|
||
}
|
||
|
||
#[test]
|
||
fn target_foundation_slot_falls_back_to_empty() {
|
||
let state = synthetic(
|
||
empty_columns(),
|
||
empty_foundations(),
|
||
Vec::new(),
|
||
Vec::new(),
|
||
DrawMode::DrawOne,
|
||
);
|
||
// No slot claims any suit; every Ace targets slot 0.
|
||
assert_eq!(state.target_foundation_slot(Suit::Spades), Some(0));
|
||
}
|
||
|
||
/// Scan a wide seed window to find one Winnable + one Unwinnable
|
||
/// seed under tight budgets. Used during development to source the
|
||
/// fixture seeds for the engine-level retry test.
|
||
/// Run with:
|
||
/// `cargo test -p solitaire_core --release -- --ignored find_unwinnable --nocapture`.
|
||
#[test]
|
||
#[ignore]
|
||
fn find_unwinnable() {
|
||
let cfg = SolverConfig::default();
|
||
let mut found = 0;
|
||
let mut counts = [0u32; 3];
|
||
for seed in 0u64..500 {
|
||
let r = try_solve(seed, DrawMode::DrawOne, &cfg);
|
||
let bucket = match r {
|
||
SolverResult::Winnable => 0,
|
||
SolverResult::Unwinnable => 1,
|
||
SolverResult::Inconclusive => 2,
|
||
};
|
||
counts[bucket] += 1;
|
||
if r == SolverResult::Unwinnable {
|
||
println!("seed {seed} -> Unwinnable");
|
||
let next = try_solve(seed.wrapping_add(1), DrawMode::DrawOne, &cfg);
|
||
println!("seed {} -> {:?}", seed.wrapping_add(1), next);
|
||
found += 1;
|
||
if found >= 5 {
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
println!(
|
||
"(scan complete) Winnable={} Unwinnable={} Inconclusive={}",
|
||
counts[0], counts[1], counts[2]
|
||
);
|
||
}
|
||
|
||
/// Manual bench — run with:
|
||
/// `cargo test -p solitaire_core --release -- --ignored solver_bench --nocapture`.
|
||
/// Prints per-seed timing and the verdict distribution so a developer
|
||
/// can sanity-check the median. Not part of the regular suite because
|
||
/// (a) it's slow and (b) timing output is noise during normal runs.
|
||
#[test]
|
||
#[ignore]
|
||
fn solver_bench() {
|
||
let cfg = SolverConfig::default();
|
||
let mut samples_ms: Vec<u128> = Vec::new();
|
||
let mut counts = [0u32; 3];
|
||
for seed in 0u64..20 {
|
||
let t = std::time::Instant::now();
|
||
let r = try_solve(seed, DrawMode::DrawOne, &cfg);
|
||
let ms = t.elapsed().as_millis();
|
||
samples_ms.push(ms);
|
||
let bucket = match r {
|
||
SolverResult::Winnable => 0,
|
||
SolverResult::Unwinnable => 1,
|
||
SolverResult::Inconclusive => 2,
|
||
};
|
||
counts[bucket] += 1;
|
||
println!("seed={seed:3} {ms:>6} ms {r:?}");
|
||
}
|
||
samples_ms.sort_unstable();
|
||
let median = samples_ms[samples_ms.len() / 2];
|
||
let total: u128 = samples_ms.iter().sum();
|
||
println!(
|
||
"\nmedian: {median} ms mean: {} ms Winnable: {} Unwinnable: {} Inconclusive: {}",
|
||
total / samples_ms.len() as u128,
|
||
counts[0], counts[1], counts[2],
|
||
);
|
||
}
|
||
|
||
// -----------------------------------------------------------------------
|
||
// First-move-recording API: try_solve_with_first_move /
|
||
// try_solve_from_state. Exercised by the engine hint system.
|
||
// -----------------------------------------------------------------------
|
||
|
||
/// A synthetic GameState with each foundation holding A..Q for its
|
||
/// suit, the four Kings sitting on tableau columns 0..3, empty stock
|
||
/// and empty waste. Exactly four legal moves exist — one Tableau→
|
||
/// Foundation per King — and any one of them is the first move on a
|
||
/// solution path.
|
||
fn near_finished_game_state() -> GameState {
|
||
use crate::card::Rank;
|
||
let mut game = GameState::new(1, DrawMode::DrawOne);
|
||
// Wipe every pile.
|
||
for slot in 0..4_u8 {
|
||
game.piles
|
||
.get_mut(&PileType::Foundation(slot))
|
||
.unwrap()
|
||
.cards
|
||
.clear();
|
||
}
|
||
for i in 0..7_usize {
|
||
game.piles
|
||
.get_mut(&PileType::Tableau(i))
|
||
.unwrap()
|
||
.cards
|
||
.clear();
|
||
}
|
||
game.piles.get_mut(&PileType::Stock).unwrap().cards.clear();
|
||
game.piles.get_mut(&PileType::Waste).unwrap().cards.clear();
|
||
|
||
// Foundations: A through Q for each suit. Slot 0=Clubs,
|
||
// 1=Diamonds, 2=Hearts, 3=Spades to match
|
||
// `target_foundation_slot` ordering.
|
||
let suit_for_slot = [Suit::Clubs, Suit::Diamonds, Suit::Hearts, Suit::Spades];
|
||
let ranks_below_king = [
|
||
Rank::Ace, Rank::Two, Rank::Three, Rank::Four, Rank::Five,
|
||
Rank::Six, Rank::Seven, Rank::Eight, Rank::Nine, Rank::Ten,
|
||
Rank::Jack, Rank::Queen,
|
||
];
|
||
for (slot, suit) in suit_for_slot.iter().enumerate() {
|
||
let pile = game
|
||
.piles
|
||
.get_mut(&PileType::Foundation(slot as u8))
|
||
.unwrap();
|
||
for (i, rank) in ranks_below_king.iter().enumerate() {
|
||
pile.cards.push(Card {
|
||
id: (slot as u32) * 13 + i as u32,
|
||
suit: *suit,
|
||
rank: *rank,
|
||
face_up: true,
|
||
});
|
||
}
|
||
}
|
||
// Tableau 0..3: one King each, face-up.
|
||
for (col, suit) in suit_for_slot.iter().enumerate() {
|
||
game.piles
|
||
.get_mut(&PileType::Tableau(col))
|
||
.unwrap()
|
||
.cards
|
||
.push(Card {
|
||
id: 100 + col as u32,
|
||
suit: *suit,
|
||
rank: Rank::King,
|
||
face_up: true,
|
||
});
|
||
}
|
||
game
|
||
}
|
||
|
||
#[test]
|
||
fn try_solve_with_first_move_returns_some_move_for_winnable_state() {
|
||
let game = near_finished_game_state();
|
||
let cfg = SolverConfig::default();
|
||
let outcome = try_solve_from_state(&game, &cfg);
|
||
assert_eq!(
|
||
outcome.result,
|
||
SolverResult::Winnable,
|
||
"near-finished state must solve as Winnable"
|
||
);
|
||
let mv = outcome.first_move.expect("Winnable must include a first_move");
|
||
// The first move must be a King going from a tableau column to
|
||
// its matching foundation slot. Single-card move.
|
||
assert_eq!(mv.count, 1);
|
||
assert!(matches!(mv.source, PileType::Tableau(c) if c < 4));
|
||
assert!(matches!(mv.dest, PileType::Foundation(s) if s < 4));
|
||
}
|
||
|
||
#[test]
|
||
fn try_solve_with_first_move_returns_none_for_unwinnable_state() {
|
||
use crate::card::Rank;
|
||
// The "buried Ace under same-suit Two with no recovery" fixture
|
||
// used by `solver_recognises_obviously_unwinnable_deal`, lifted
|
||
// into a real `GameState` so we can exercise `try_solve_from_state`.
|
||
let mut game = GameState::new(1, DrawMode::DrawOne);
|
||
for slot in 0..4_u8 {
|
||
game.piles
|
||
.get_mut(&PileType::Foundation(slot))
|
||
.unwrap()
|
||
.cards
|
||
.clear();
|
||
}
|
||
for i in 0..7_usize {
|
||
game.piles
|
||
.get_mut(&PileType::Tableau(i))
|
||
.unwrap()
|
||
.cards
|
||
.clear();
|
||
}
|
||
game.piles.get_mut(&PileType::Stock).unwrap().cards.clear();
|
||
game.piles.get_mut(&PileType::Waste).unwrap().cards.clear();
|
||
// Tableau 0: A♠ on the bottom, 2♠ on top — the 2♠ has no legal
|
||
// destination, so the Ace is buried forever.
|
||
let t0 = game.piles.get_mut(&PileType::Tableau(0)).unwrap();
|
||
t0.cards.push(Card { id: 0, suit: Suit::Spades, rank: Rank::Ace, face_up: true });
|
||
t0.cards.push(Card { id: 1, suit: Suit::Spades, rank: Rank::Two, face_up: true });
|
||
// Tableau 1: a face-up King with nothing else — irrelevant; the
|
||
// pruning check elides "King → empty" no-ops.
|
||
game.piles
|
||
.get_mut(&PileType::Tableau(1))
|
||
.unwrap()
|
||
.cards
|
||
.push(Card { id: 2, suit: Suit::Clubs, rank: Rank::King, face_up: true });
|
||
|
||
let cfg = SolverConfig::default();
|
||
let outcome = try_solve_from_state(&game, &cfg);
|
||
assert_eq!(
|
||
outcome.result,
|
||
SolverResult::Unwinnable,
|
||
"buried-Ace fixture must be proved Unwinnable"
|
||
);
|
||
assert!(
|
||
outcome.first_move.is_none(),
|
||
"Unwinnable verdict must carry first_move == None"
|
||
);
|
||
}
|
||
|
||
#[test]
|
||
fn try_solve_with_first_move_is_deterministic() {
|
||
// Same state run multiple times yields the same first_move.
|
||
let game = near_finished_game_state();
|
||
let cfg = SolverConfig::default();
|
||
let a = try_solve_from_state(&game, &cfg);
|
||
let b = try_solve_from_state(&game, &cfg);
|
||
let c = try_solve_from_state(&game, &cfg);
|
||
assert_eq!(a, b, "repeat solves must yield the same outcome");
|
||
assert_eq!(b, c);
|
||
}
|
||
|
||
#[test]
|
||
fn try_solve_with_first_move_seed_form_matches_state_form() {
|
||
// For a fresh seed, the two public entry points must agree —
|
||
// they share the same internal `solve()` implementation, but
|
||
// route through different state constructors. This is the
|
||
// smoke test that catches drift between them.
|
||
let cfg = SolverConfig {
|
||
move_budget: 5_000,
|
||
state_budget: 5_000,
|
||
};
|
||
let a = try_solve_with_first_move(7, DrawMode::DrawOne, &cfg);
|
||
let game = GameState::new(7, DrawMode::DrawOne);
|
||
let b = try_solve_from_state(&game, &cfg);
|
||
assert_eq!(a.result, b.result, "verdicts must match across the two entry points");
|
||
assert_eq!(a.first_move, b.first_move, "first_move must match across the two entry points");
|
||
}
|
||
}
|