Data update

Task/Sokoban/JavaScript/sokoban.js

@@ -0,0 +1,130 @@
+class Sokoban {
+    constructor(board) {
+        this.nCols = board[0].length;
+        let destBuf = '';
+        let currBuf = '';
+
+        for (let r = 0; r < board.length; r++) {
+            for (let c = 0; c < this.nCols; c++) {
+                const ch = board[r].charAt(c);
+
+                destBuf += (ch !== '$' && ch !== '@') ? ch : ' ';
+                currBuf += (ch !== '.') ? ch : ' ';
+
+                if (ch === '@') {
+                    this.playerX = c;
+                    this.playerY = r;
+                }
+            }
+        }
+        this.destBoard = destBuf;
+        this.currBoard = currBuf;
+    }
+
+    move(x, y, dx, dy, trialBoard) {
+        const newPlayerPos = (y + dy) * this.nCols + x + dx;
+
+        if (trialBoard.charAt(newPlayerPos) !== ' ') {
+            return null;
+        }
+
+        const trial = trialBoard.split('');
+        trial[y * this.nCols + x] = ' ';
+        trial[newPlayerPos] = '@';
+
+        return trial.join('');
+    }
+
+    push(x, y, dx, dy, trialBoard) {
+        const newBoxPos = (y + 2 * dy) * this.nCols + x + 2 * dx;
+
+        if (trialBoard.charAt(newBoxPos) !== ' ') {
+            return null;
+        }
+
+        const trial = trialBoard.split('');
+        trial[y * this.nCols + x] = ' ';
+        trial[(y + dy) * this.nCols + x + dx] = '@';
+        trial[newBoxPos] = '$';
+
+        return trial.join('');
+    }
+
+    isSolved(trialBoard) {
+        for (let i = 0; i < trialBoard.length; i++) {
+            if ((this.destBoard.charAt(i) === '.') !== (trialBoard.charAt(i) === '$')) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    solve() {
+        class Board {
+            constructor(cur, sol, x, y) {
+                this.cur = cur;
+                this.sol = sol;
+                this.x = x;
+                this.y = y;
+            }
+        }
+
+        const dirLabels = [['u', 'U'], ['r', 'R'], ['d', 'D'], ['l', 'L']];
+        const dirs = [[0, -1], [1, 0], [0, 1], [-1, 0]];
+
+        const history = new Set();
+        const open = [];
+
+        history.add(this.currBoard);
+        open.push(new Board(this.currBoard, "", this.playerX, this.playerY));
+
+        while (open.length > 0) {
+            const item = open.shift(); // poll() equivalent
+            const cur = item.cur;
+            const sol = item.sol;
+            const x = item.x;
+            const y = item.y;
+
+            for (let i = 0; i < dirs.length; i++) {
+                let trial = cur;
+                const dx = dirs[i][0];
+                const dy = dirs[i][1];
+
+                // are we standing next to a box?
+                if (trial.charAt((y + dy) * this.nCols + x + dx) === '$') {
+                    // can we push it?
+                    trial = this.push(x, y, dx, dy, trial);
+                    if (trial !== null) {
+                        // or did we already try this one?
+                        if (!history.has(trial)) {
+                            const newSol = sol + dirLabels[i][1];
+
+                            if (this.isSolved(trial)) {
+                                return newSol;
+                            }
+
+                            open.push(new Board(trial, newSol, x + dx, y + dy));
+                            history.add(trial);
+                        }
+                    }
+                // otherwise try changing position
+                } else {
+                    trial = this.move(x, y, dx, dy, trial);
+                    if (trial !== null) {
+                        if (!history.has(trial)) {
+                            const newSol = sol + dirLabels[i][0];
+                            open.push(new Board(trial, newSol, x + dx, y + dy));
+                            history.add(trial);
+                        }
+                    }
+                }
+            }
+        }
+        return "No solution";
+    }
+}
+
+// Example usage
+const level = "#######,#     #,#     #,#. #  #,#. $$ #,#.$$  #,#.#  @#,#######";
+const sokoban = new Sokoban(level.split(","));
+console.log(sokoban.solve());