solve: W04 word search

Author: eunice-hong

word-search/eunice-hong.ts

@@ -0,0 +1,45 @@
+
+/**
+ * Time Complexity: O(m * n * 4^k)
+ * Space Complexity: O(m * n)
+ */
+function exist(board: string[][], word: string): boolean {
+  // Initialize the board dimensions
+  const m = board.length;
+  const n = board[0].length;
+
+  const dfs = (i: number, j: number, index: number): boolean => {
+    // If we've matched all characters, return true
+    if (index === word.length) return true;
+    // If out of bounds or current character doesn't match, return false
+    if (i < 0 || i >= m || j < 0 || j >= n || board[i][j] !== word[index]) return false;
+
+    // Temporarily mark the current cell as visited
+    const temp = board[i][j];
+    board[i][j] = '#';
+
+    // Explore all four possible directions
+    const found =
+      dfs(i + 1, j, index + 1) ||
+      dfs(i - 1, j, index + 1) ||
+      dfs(i, j + 1, index + 1) ||
+      dfs(i, j - 1, index + 1);
+
+    // Unmark the current cell (backtracking)
+    board[i][j] = temp;
+
+    // Return true if we found the word
+    return found;
+  };
+
+  // Iterate through each cell in the board
+  for (let i = 0; i < m; i++) {
+    for (let j = 0; j < n; j++) {
+      // Start DFS from each cell
+      if (dfs(i, j, 0)) return true;
+    }
+  }
+
+  // If we didn't find the word, return false
+  return false;
+}