```cpp
#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int f[33][33];
int x,y,i,j,n;
bool flag[33][33];
int dx[5]={0,1,0,-1,0},dy[5]={0,0,1,0,-1};
void work(int i,int j){
if(f[i][j]==1||flag[i][j]==1||i==n+1||i==-1||j==-1||j==n+1)return;
int a;
flag[i][j]=1;
for(a=1;a<=4;a++)work(i+dx[a],j+dy[a]);
return;
}
int main(){
memset(flag,0,sizeof flag);
scanf("%d",&n);
for(i=1;i<=n;i++){
for(j=1;j<=n;j++){
scanf("%d",&f[i][j]);
if(f[i][j])flag[i][j]=1;
}
}
for(i=1;i<=n;i++){
work(i,1);
work(1,i);
work(n,i);
work(i,n);
}
for(i=1;i<=n;i++){
for(j=1;j<=n;j++){
if(flag[i][j])
printf("%d ",f[i][j]);
else
printf("2 ");
}
printf("\n");
}
return 0;
}
AC代码（求关注）
by LEZ2012 @ 2023-04-09 21:00:49