Add word-search solution in TypeScript

Author: Jeehay28

word-search/Jeehay28.ts

@@ -0,0 +1,46 @@
+// Time Complexity: O(m * n * 4^L), where L is the length of the word
+// Space Complexity: O(L) due to he recursive call stack
+
+function exist(board: string[][], word: string): boolean {
+  // input: m * n grid of characters board, a string word
+  // output: true if word exists in the grid
+
+  const dfs = (index: number, row: number, col: number) => {
+    if (
+      row < 0 ||
+      row >= board.length ||
+      col < 0 ||
+      col >= board[0].length ||
+      board[row][col] !== word[index]
+    ) {
+      return false;
+    }
+
+    if (index === word.length - 1) {
+      return true;
+    }
+
+    const visited = board[row][col];
+    board[row][col] = "#";
+
+    const result =
+      dfs(index + 1, row + 1, col) ||
+      dfs(index + 1, row - 1, col) ||
+      dfs(index + 1, row, col + 1) ||
+      dfs(index + 1, row, col - 1);
+
+    board[row][col] = visited;
+
+    return result;
+  };
+
+  for (let i = 0; i < board.length; i++) {
+    for (let j = 0; j < board[0].length; j++) {
+      if (dfs(0, i, j)) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+}