exist.js

var exist = function(board, word) {
    const dfs = (i, j, k) => {
        // Base case: If k reaches the end of the word, return True
        if (k === word.length) {
            return true;
        }
        // Check if the current cell is out of bounds or does not match the word
        if (
            i < 0 ||
            i >= board.length ||
            j < 0 ||
            j >= board[0].length ||
            board[i][j] !== word[k]
        ) {
            return false;
        }
        // Mark the current cell as visited (temporarily change its value)
        const temp = board[i][j];
        board[i][j] = '/'; // Use any character to indicate visited cell
        // Explore adjacent cells (up, down, left, right)
        const found =
            dfs(i + 1, j, k + 1) ||
            dfs(i - 1, j, k + 1) ||
            dfs(i, j + 1, k + 1) ||
            dfs(i, j - 1, k + 1);
        // Restore the original value of the cell
        board[i][j] = temp;
        return found;
    };

    // Iterate through each cell in the grid
    for (let i = 0; i < board.length; i++) {
        for (let j = 0; j < board[0].length; j++) {
            if (board[i][j] === word[0] && dfs(i, j, 0)) {
                return true;
            }
        }
    }
    return false;
};