Add solver for double back (#205)

* Added solver for double back

* Simplified constraints

Author: ReverM

cspuz_rs_puzzles/src/puzzles/doubleback.rs

@@ -0,0 +1,121 @@
+use cspuz_rs::graph;
+use cspuz_rs::serializer::{
+    problem_to_url_with_context, url_to_problem, Combinator, Context, Rooms, Size,
+};
+use cspuz_rs::solver::{count_true, Solver};
+
+pub fn solve_doubleback(
+    borders: &graph::InnerGridEdges<Vec<Vec<bool>>>,
+) -> Option<graph::BoolGridEdgesIrrefutableFacts> {
+    let (h, w) = borders.base_shape();
+
+    let mut solver = Solver::new();
+    let rooms = graph::borders_to_rooms(borders);
+    let is_line = &graph::BoolGridEdges::new(&mut solver, (h - 1, w - 1));
+    solver.add_answer_key_bool(&is_line.horizontal);
+    solver.add_answer_key_bool(&is_line.vertical);
+
+    let is_passed = &graph::single_cycle_grid_edges(&mut solver, is_line);
+    let mut room_id = vec![vec![0; w]; h];
+
+    for i in 0..rooms.len() {
+        for &(y, x) in &rooms[i] {
+            room_id[y][x] = i;
+        }
+    }
+
+    let mut room_entrance = vec![vec![]; rooms.len()];
+    for y in 0..h {
+        for x in 0..w {
+            if y < h - 1 && room_id[y][x] != room_id[y + 1][x] {
+                room_entrance[room_id[y][x]].push(is_line.vertical.at((y, x)));
+                room_entrance[room_id[y + 1][x]].push(is_line.vertical.at((y, x)));
+            }
+            if x < w - 1 && room_id[y][x] != room_id[y][x + 1] {
+                room_entrance[room_id[y][x]].push(is_line.horizontal.at((y, x)));
+                room_entrance[room_id[y][x + 1]].push(is_line.horizontal.at((y, x)));
+            }
+        }
+    }
+
+    for i in 0..rooms.len() {
+        // Check every room is entered twice
+        solver.add_expr(count_true(&room_entrance[i]).eq(4));
+    }
+
+    for i in 0..rooms.len() {
+        let mut cells = vec![];
+        for &pt in &rooms[i] {
+            cells.push(is_passed.at(pt));
+        }
+    }
+
+    solver.add_expr(is_passed);
+
+    solver.irrefutable_facts().map(|f| f.get(is_line))
+}
+
+type Problem = graph::InnerGridEdges<Vec<Vec<bool>>>;
+
+fn combinator() -> impl Combinator<Problem> {
+    Size::new(Rooms)
+}
+
+pub fn serialize_problem(problem: &Problem) -> Option<String> {
+    let height = problem.vertical.len();
+    let width = problem.vertical[0].len() + 1;
+    problem_to_url_with_context(
+        combinator(),
+        "doubleback",
+        problem.clone(),
+        &Context::sized(height, width),
+    )
+}
+
+pub fn deserialize_problem(url: &str) -> Option<Problem> {
+    url_to_problem(combinator(), &["doubleback"], url)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::util;
+
+    fn problem_for_tests() -> Problem {
+        let borders = graph::InnerGridEdges {
+            horizontal: crate::util::tests::to_bool_2d([[0, 0, 1, 1], [0, 0, 0, 0], [1, 1, 1, 1]]),
+            vertical: crate::util::tests::to_bool_2d([[0, 0, 0], [0, 1, 0], [0, 1, 0], [0, 0, 0]]),
+        };
+        borders
+    }
+
+    #[test]
+    fn test_doubleback_problem() {
+        let borders = problem_for_tests();
+        let ans = solve_doubleback(&borders);
+        assert!(ans.is_some());
+        let ans = ans.unwrap();
+
+        #[rustfmt::skip]
+        let expected = graph::BoolGridEdgesIrrefutableFacts {
+            horizontal: crate::util::tests::to_option_bool_2d([
+                [1, 1, 1],
+                [0, 1, 0],
+                [0, 0, 0],
+                [1, 0, 1],
+            ]),
+            vertical: crate::util::tests::to_option_bool_2d([
+                [1, 0, 0, 1],
+                [1, 1, 1, 1],
+                [1, 1, 1, 1],
+            ]),
+        };
+        assert_eq!(ans, expected);
+    }
+    #[test]
+    fn test_doubleback_serializer() {
+        let problem = problem_for_tests();
+        let url = "https://puzz.link/p?doubleback/4/4/14063o"; // puzz.link example puzzle
+        util::tests::serializer_test(problem, url, serialize_problem, deserialize_problem);
+    }
+}

cspuz_rs_puzzles/src/puzzles/mod.rs

@@ -36,6 +36,7 @@ pub mod dbchoco;
 pub mod dominion;
 pub mod doppelblock;
 pub mod double_lits;
+pub mod doubleback;
 pub mod energywalk;
 pub mod evolmino;
 pub mod exercise;

cspuz_solver_backend/src/puzzle/doubleback.rs

@@ -0,0 +1,75 @@
+use crate::board::{Board, BoardKind};
+use crate::uniqueness::check_uniqueness;
+use cspuz_rs_puzzles::puzzles::doubleback;
+
+pub fn solve(url: &str) -> Result<Board, &'static str> {
+    let borders = doubleback::deserialize_problem(url).ok_or("invalid url")?;
+    let ans = doubleback::solve_doubleback(&borders);
+
+    let height = borders.vertical.len();
+    let width = borders.vertical[0].len() + 1;
+    let mut board = Board::new(BoardKind::Grid, height, width, check_uniqueness(&ans));
+    board.add_borders(&borders, "black");
+
+    if let Some(is_line) = &ans {
+        board.add_lines_irrefutable_facts(is_line, "green", None);
+    }
+
+    Ok(board)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::solve;
+    use crate::board::*;
+    use crate::compare_board_and_check_no_solution_case;
+    use crate::uniqueness::Uniqueness;
+
+    #[test]
+    #[rustfmt::skip]
+    fn test_solve() {
+        compare_board_and_check_no_solution_case!(
+            solve("https://puzz.link/p?doubleback/4/4/14063o"),
+            Board {
+                kind: BoardKind::Grid,
+                height: 4,
+                width: 4,
+                data: vec![
+                    Item { y: 2, x: 5, color: "black", kind: ItemKind::BoldWall }, 
+                    Item { y: 2, x: 7, color: "black", kind: ItemKind::BoldWall }, 
+                    Item { y: 3, x: 4, color: "black", kind: ItemKind::BoldWall }, 
+                    Item { y: 6, x: 1, color: "black", kind: ItemKind::BoldWall }, 
+                    Item { y: 6, x: 3, color: "black", kind: ItemKind::BoldWall }, 
+                    Item { y: 5, x: 4, color: "black", kind: ItemKind::BoldWall }, 
+                    Item { y: 6, x: 5, color: "black", kind: ItemKind::BoldWall }, 
+                    Item { y: 6, x: 7, color: "black", kind: ItemKind::BoldWall }, 
+                    Item { y: 2, x: 1, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 2, x: 3, color: "green", kind: ItemKind::Cross }, 
+                    Item { y: 2, x: 5, color: "green", kind: ItemKind::Cross }, 
+                    Item { y: 2, x: 7, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 4, x: 1, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 4, x: 3, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 4, x: 5, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 4, x: 7, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 6, x: 1, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 6, x: 3, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 6, x: 5, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 6, x: 7, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 1, x: 2, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 1, x: 4, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 1, x: 6, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 3, x: 2, color: "green", kind: ItemKind::Cross }, 
+                    Item { y: 3, x: 4, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 3, x: 6, color: "green", kind: ItemKind::Cross }, 
+                    Item { y: 5, x: 2, color: "green", kind: ItemKind::Cross }, 
+                    Item { y: 5, x: 4, color: "green", kind: ItemKind::Cross }, 
+                    Item { y: 5, x: 6, color: "green", kind: ItemKind::Cross }, 
+                    Item { y: 7, x: 2, color: "green", kind: ItemKind::Line }, 
+                    Item { y: 7, x: 4, color: "green", kind: ItemKind::Cross }, 
+                    Item { y: 7, x: 6, color: "green", kind: ItemKind::Line },
+                ],
+                uniqueness: Uniqueness::Unique,
+            },
+        );
+    }
+}

cspuz_solver_backend/src/puzzle/mod.rs

@@ -118,6 +118,7 @@ puzzle_list!(puzz_link,
     (dbchoco, ["dbchoco"], "Double Choco", "ダブルチョコ"),
     (dominion, ["dominion"], "Dominion", "ドミニオン"),
     (doppelblock, ["doppelblock"], "Doppelblock", "ビトゥイーン・サム"),
+    (doubleback, ["doubleback"], "Double Back", "Double Back"),
     (energywalk, ["energywalk"], "Energy Walk", "Energy Walk"),
     (evolmino, ["evolmino"], "Evolmino", "シンカミノ"),
     (fillomino, ["fillomino"], "Fillomino", "フィルオミノ"),