Update 79-word-search.js

Author: everthis

79-word-search.js

@@ -34,3 +34,43 @@ function dfs(board, x, y, dirs, word, start) {
 
   return false;
 }
+
+// another
+
+/**
+ * @param {character[][]} board
+ * @param {string} word
+ * @return {boolean}
+ */
+const exist = function(board, word) {
+  if (!word || !board || board.length === 0) return false
+  const dirs = [[-1, 0], [1, 0], [0, -1], [0, 1]]
+  for (let row = 0; row < board.length; row++) {
+    for (let col = 0; col < board[row].length; col++) {
+      if (searchWord(board, row, col, word, 0, dirs)) return true
+    }
+  }
+  return false
+}
+
+const searchWord = (board, row, col, word, widx, dirs) => {
+  if (widx === word.length) return true
+  if (
+    row < 0 ||
+    col < 0 ||
+    row === board.length ||
+    col === board[0].length ||
+    board[row][col] === null ||
+    board[row][col] !== word[widx]
+  ) return false
+
+  const ch = board[row][col]
+  board[row][col] = null // mark visited
+
+  for (let dir of dirs) {
+    if (searchWord(board, row + dir[0], col + dir[1], word, widx + 1, dirs)) {
+      return true
+    }
+  }
+  board[row][col] = ch // recover
+}