Add word-search solution

Author: Jeehay28

word-search/Jeehay28.js

@@ -0,0 +1,67 @@
+/**
+ * @param {character[][]} board
+ * @param {string} word
+ * @return {boolean}
+ */
+
+// board(N * M), where N is the number of row and M is the number of columns
+// L, the length of the word
+// TC : O(N * M * 4^L)
+
+// recursion depth : the length of the word (L)
+// each recursion call requires constant space.
+// SC : O(L)
+
+var exist = function (board, word) {
+  let row = board.length;
+  let col = board[0].length;
+
+  const dfs = (r, c, idx) => {
+    // search done
+    if (idx === word.length) {
+      return true;
+    }
+
+    // row and column are out of range
+    if (r < 0 || r >= row || c < 0 || c >= col) {
+      return false;
+    }
+
+    if (board[r][c] !== word[idx]) {
+      return false;
+    }
+
+    // word[idx] === board[r][c]
+    // continue searching for word[idx + 1] in adjacent cells on the board
+    const temp = board[r][c];
+    board[r][c] = "visited";
+
+    const arr = [
+      [1, 0], // Move down
+      [-1, 0], // Move up
+      [0, 1], // Move right
+      [0, -1], // Move left
+    ];
+    for (const [up, right] of arr) {
+      if (dfs(r + up, c + right, idx + 1)) {
+        return true;
+      }
+    }
+
+    board[r][c] = temp;
+    return false;
+  };
+
+  for (let i = 0; i < row; i++) {
+    for (let j = 0; j < col; j++) {
+      if (dfs(i, j, 0)) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+};
+
+
+