P1162 填充颜色

1. 题目链接：https://www.luogu.org/problemnew/show/P1162

2. AC code:

#include<iostream>
using namespace std;
int a[37][37],n;
void dfs(int x,int y){
    if(x>=0&&x<=n+1&&y>=0&&y<=n+1){
        if(a[x][y]==1||a[x][y]==3)return ;
        else {
            a[x][y]=3;
            dfs(x+1,y);dfs(x-1,y);
            dfs(x,y+1);dfs(x,y-1);
        }
    }
}
int main(){
    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(a[i][j]==0)a[i][j]=2;
            if(a[i][j]==3)a[i][j]=0;
        }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++)cout<<a[i][j]<<" ";
        cout<<endl;
    }
}