本地可通过，leetcode越界

Question

剑指offer12

问题相关代码

class Solution {
public:
    bool flag;
    vector<int> mx = {1,-1,0,0};
    vector<int> my = {0,0,1,-1};
    int nx,ny;
    bool exist(vector<vector<char>>& board, string word) {
        flag = false;
        for(int i=0; i<board.size(); i++){
            for(int j=0; j<board[0].size(); j++){
                if(!flag&&board[i][j]==word[0]){
                    board[i][j] = '\0';
                    backReverse(board, word, 1, i, j);
                    board[i][j] = word[0];
                }
            }
        }
        return flag;
    }

    void backReverse(vector<vector<char>>& board, string& word, int ind, int x, int y){
        if(ind==word.size()){
            flag = true;
        }
        for(int i=0; i<4; i++){
            nx = mx[i]+x;
            ny = my[i]+y;
            if(!flag&&nx>=0&&nx<board.size()&&ny>=0&&ny<board[0].size()&&board[nx][ny]!=1){
                if(board[nx][ny]==word[ind]){
                    board[nx][ny] = '\0';
                    backReverse(board, word, ind+1, nx, ny);
                    board[nx][ny] = word[ind];
                }
            }
        }

    }
};

运行结果及报错内容

Line 1033: Char 34: runtime error: addition of unsigned offset to 0x602000000090 overflowed to 0x60200000008f (stl_vector.h)
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_vector.h:1043:34

我的解答思路和尝试过的方法

我想要达到的结果

Answer 1

题目是什么