Implement robotPaths.js

robotPaths/robotPaths.js

@@ -11,24 +11,58 @@
 
 // A Board class will be useful
 
-var makeBoard = function(n) {
+var makeBoard = function (n) {
   var board = [];
+
   for (var i = 0; i < n; i++) {
     board.push([]);
     for (var j = 0; j < n; j++) {
       board[i].push(false);
     }
   }
-  board.togglePiece = function(i, j) {
+
+  board.togglePiece = function (i, j) {
     this[i][j] = !this[i][j];
-  }
-  board.hasBeenVisited = function(i, j) {
+  };
+
+  board.hasBeenVisited = function (i, j) {
     return !!this[i][j];
-  }
+  };
+
+  board.withInBoard = function (i, j) {
+    return (i >= 0 && i < n && j >= 0 && j < n);
+  };
+
   return board;
 };
 
-var robotPaths = function(n) {
-  // YOUR CODE HERE
-}
+var robotPaths = function (n) {
+  var total = 0;
+  var board = makeBoard(n);
+  var inner = function (board, x, y) {
+    // base case
+    if (x === n - 1 && y === n - 1 && !board.hasBeenVisited(x, y)) {
+      total += 1;
+      return;
+    }
+
+    if (board.withInBoard(x, y) && !board.hasBeenVisited(x, y)) {
+      board.togglePiece(x, y);
+
+      // check left position
+      inner(board, x - 1, y);
+      // check right position
+      inner(board, x + 1, y);
+      // check top position
+      inner(board, x, y - 1);
+      // check bottom position
+      inner(board, x, y + 1);
+
+      // untoggle current position
+      board.togglePiece(x, y);
+    }
+  };
 
+  inner(board, 0, 0);
+  return total;
+};