改成这样
```cpp
#include <bits/stdc++.h>
using namespace std;
struct NODE {
int x, y;
};
queue <NODE> q;
int n, x, y, nextx, nexty, dis[10001][1001], instartx, instarty, tarx, tary, dx[4] = {1, -1, 0, 0}, dy[4] = {0, 0, 1, -1};
char MAP[10001][1001];
bool vis[10001][1001];
int bfs(int startx, int starty) {
q.push((NODE){startx, starty});
vis[startx][starty] = true;
while (!q.empty()) {
x = q.front().x;
y = q.front().y;
q.pop();
if (x == tarx && y == tary) {
return dis[x][y];
}
for (int i = 0; i < 4; i++) {
nextx = x + dx[i];
nexty = y + dy[i];
if ((MAP[nextx][nexty] == '1' || vis[nextx][nexty] == true) || (nextx <= 0 || nextx > n || nexty <= 0 || nexty > n)) {
continue;
}
dis[nextx][nexty] = dis[x][y] + 1;
vis[nextx][nexty] = true;
q.push((NODE){nextx, nexty});
}
}
return -1;
}
int main() {
cin >> n;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
cin >> MAP[i][j];
}
}
cin >> instartx >> instarty >> tarx >> tary;
cout << bfs(instartx, instarty) << endl;
return 0;
}
```
by qfpjm @ 2021-10-07 16:31:50
@[任宇宸](/user/250291)
by qfpjm @ 2021-10-07 16:32:15
@[Ted何家乐](/user/342868) AC 了，感谢！！！
by yuchenren @ 2021-10-07 16:36:07