class Solution {
public:

    bool backtracking(vector<vector<char>>& board, string& word, int index, int row, int col) {
        if(index == word.size()) {
            return true;
        }

        if(row < 0 || row == board.size() || col < 0 || col == board[0].size() || word[index] != board[row][col]) {
            return false;
        }

        board[row][col] = '#';
        
        bool r1 = backtracking(board, word, index + 1, row + 1, col);
        bool r2 = backtracking(board, word, index + 1, row - 1, col);
        bool r3 = backtracking(board, word, index + 1, row, col + 1);
        bool r4 = backtracking(board, word, index + 1, row, col - 1);

        board[row][col] = word[index];

        return r1 || r2 || r3 || r4;
    }

    bool exist(vector<vector<char>>& board, string word) {
        for(int i = 0; i < board.size(); i++) {
            for(int j = 0; j < board[0].size(); j++) {
                if(backtracking(board, word, 0, i, j) == true) {
                    return true;
                }
            }
        }
        
        return false;
    }
};