一直挂第四个点，请大佬指正错误

我也不知道为什么非要写BFS折磨自己qwq

#include<iostream>
#include<queue>
using namespace std;
int n, map[35][35];
bool vis[35][35];
int to[5][2] = {{0, 0}, {1, 0}, {0, 1}, {-1, 0}, {0, -1}};
struct node {
	int x, y;
};
queue<node> q;
inline void bfs(int a, int b) {
	node t = {a, b};
	q.push(t);
	vis[a][b] = 1;
	while(!q.empty()) {
		node k = q.front();
		int xx = k.x, yy = k.y;
		q.pop();
		for(int i = 1; i <= 4; i++) {
			int kx = xx + to[i][0], ky = yy + to[i][1];
			if(!vis[kx][ky] and kx > 0 and kx <= n and ky > 0 and ky <= n) {
				vis[kx][ky] = 1;
				node tmp = {kx, ky};
				q.push(tmp);
			}
		}
	}
}
int main() {
	cin>>n;
	for(int i = 1; i <= n; i++)
	    for(int j = 1; j <= n; j++)
	        cin>>map[i][j];
	for(int i = 1; i <= n; i++)
	    for(int j = 1; j <= n; j++)
	        if(map[i][j] == 1)
	            vis[i][j] = 1;
	for(int i = 1; i <= n; i++)
	    if(map[i][1] == 0 and !vis[i][1])
	        bfs(i, 1);
	for(int i = 1; i <= n; i++)
	    if(map[i][n] == 0 and !vis[i][n])
	        bfs(i, n);
	for(int i = 1; i <= n; i++)
	    if(map[1][i] == 0 and !vis[1][i])
	        bfs(1, i);
	for(int i = 1; i <= n; i++)
	    if(map[1][n] == 0 and !vis[1][n])
	        bfs(n, i);
	for(int i = 1; i <= n; i++)
	    for(int j = 1; j <= n; j++) {
	    	if(!vis[i][j] and map[i][j] == 0)
	    	    map[i][j] = 2;
		}
	for(int i = 1; i <= n; i++) {
		for(int j = 1; j <= n; j++)
		    cout<<map[i][j]<<" ";
		cout<<'\n';
	}
	return 0;
}