Added wordSearch solution

Author: nhistory

word-search/nhistory.js

@@ -0,0 +1,36 @@
+var exist = function (board, word) {
+  const dfs = (row, col, index) => {
+    if (word.length === index) return true;
+    if (
+      row < 0 ||
+      col < 0 ||
+      row >= board.length ||
+      col >= board[0].length ||
+      board[row][col] !== word[index]
+    )
+      return false;
+
+    board[row][col] = "#";
+    if (
+      dfs(row + 1, col, index + 1) ||
+      dfs(row, col + 1, index + 1) ||
+      dfs(row - 1, col, index + 1) ||
+      dfs(row, col - 1, index + 1)
+    )
+      return true;
+
+    board[row][col] = word[index];
+  };
+
+  for (let row = 0; row < board.length; row++) {
+    for (let col = 0; col < board[row].length; col++) {
+      if (board[row][col] === word[0] && dfs(row, col, 0)) return true;
+    }
+  }
+
+  return false;
+};
+
+// N: board column length / M: board row length / L: word length
+// TC: O(N*M*4^L)
+// SC: O(L)