萌新求助，为啥0分

我直接用STL的queue，还RE一个点

#include <cstdio>
#include <queue>
#include <iostream>
#include <cstring>
int dx[4] = {1 , 0 , -1 , 0} , dy[4] = {0 , 1 , 0 , -1};
int n , m , sx , sy , ex , ey;
bool map[1003][1003];
bool v[1003][1003];
struct node {
    int x , y , sp;
};
int main() {
    scanf("%d" , &n);
    char c = getchar();
    memset(map , 0 , sizeof(map));
    for (int i = 1 ; i <= n ; i++) {
        for (int j = 1 ; j <= n ; j++) {
            c = getchar();
            if (c == '0') map[i][j] = 1;
        }
        getchar();
    }
    scanf("%d%d%d%d" , &sx , &sy , &ex , &ey);
    std::queue <node> q;
    q.push((node){sx , sy , 0});
    v[sx][sy] = 1;
    while (!q.empty()) {
        node g = q.front();
        q.pop();
        for (int i = 0 ; i < 4 ; i++) {
            int tx = g.x + dx[i] , ty = g.y + dy[i];
            if (tx <= n && tx >= 1 && ty <= n && ty >= 1 && !v[tx][ty] && map[tx][ty]) {
                q.push((node){tx , ty , g.sp + 1});
                v[tx][ty] = 1;
                if (tx == ex && ty == ey) {
                    printf("%d" , g.sp + 1);
                    return 0;
                }
            }
        }
    }
    return 0;
}