leetcode-79-word search

class Solution {
public:
    bool (vector<vector<char> >& board, string word) {
        int rows = board.size();
        int cols = board[0].size();
        for(int i = 0; i < rows; i++){
            for(int j = 0; j < cols; j++){
                if(isFound(board, word, 0, i, j))
                    return true;
            }
        }
        return false;
    }

    bool isFound(vector<vector<char> > &board, string word, int len, int i, int j){
        if(i < 0 || i >= board.size() || j < 0 || j >= board[0].size() || board[i][j] == '