求助

样例没过，找不出来了，求助

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<algorithm>
using namespace std;
typedef long long ll;
int n,a[50][50],X[4]={1,-1,0,0},Y[4]={0,0,1,-1},tmp[50][50]; 
void dfs(int x,int y){
    for(int i=0;i<4;i++){
        int idx=x+X[i],idy=y+Y[i];
        if(idx<1 || idy<1 || idx>n || idy>n || tmp[idx][idy] || a[idx][idy]==1) continue;
        tmp[idx][idy]=1;
        dfs(idx,idy);
    }
    return ;
}
int main(){
//  freopen(".in","r",stdin);
//  freopen(".out","w",stdout);
    ios::sync_with_stdio(false);
    cin.tie(0),cout.tie(0);
    cin>>n;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            cin>>a[i][j];
        }
    }
    dfs(0,0);
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(tmp[i][j]==0 && a[i][j]==0){
                a[i][j]=2;
            }
            cout<<a[i][j]<<" ";
        }
        cout<<endl;
    }
//  fclose(stdin);
//  fclose(stdout);
    return 0;
}