求助！

first_king @ 2023-09-07 21:54:44

#include <bits/stdc++.h>
using namespace std;
int dx[4]={-1,1,0,0};
int dy[4]={0,0,-1,1};
int a[1001][1001],n;
bool vis[1001][1001];
void dfs(int x,int y){
    if(x<0||x>n||y<0||y>n||vis[x][y]!=0) return ;
    vis[x][y]=1;
    for(int i=0;i<4;i++) dfs(x+dx[i],y+dy[i]);
}
signed main(){
    cin>>n;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            cin>>a[i][j];
            if(a[i][j]==0) vis[i][j]=0;
            else vis[i][j]=2;
        }
    }
    dfs(1,1);
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(vis[i][j]==0) cout<<2<<" ";
            else cout<<a[i][j]<<" ";
        }
        cout<<endl;
    }
    return 0;
} 

by One_JuRuo @ 2023-09-07 21:59:51

@first_king

显然不能从 (1,1) dfs。

hack：

6
1 1 1 1 1 0
1 0 0 1 0 0
1 0 1 1 0 0
1 1 1 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0

by first_king @ 2023-09-07 22:01:19

@One_JuRuo 能不能帮我改一下代码

by One_JuRuo @ 2023-09-07 22:01:43

@first_king 从四个角搜索应该就对了，不太清楚，可以自己去试试。

#include <bits/stdc++.h>
using namespace std;
int dx[4]={-1,1,0,0};
int dy[4]={0,0,-1,1};
int a[1001][1001],n;
bool vis[1001][1001];
void dfs(int x,int y){
    if(x<0||x>n||y<0||y>n||vis[x][y]!=0) return ;
    vis[x][y]=1;
    for(int i=0;i<4;i++) dfs(x+dx[i],y+dy[i]);
}
signed main(){
    cin>>n;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            cin>>a[i][j];
            if(a[i][j]==0) vis[i][j]=0;
            else vis[i][j]=2;
        }
    }
    dfs(1,1),dfs(n,n),dfs(1,n),dfs(n,1);
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(vis[i][j]==0) cout<<2<<" ";
            else cout<<a[i][j]<<" ";
        }
        cout<<endl;
    }
    return 0;
} 

by first_king @ 2023-09-07 22:03:08

@One_JuRuo 48分

by One_JuRuo @ 2023-09-07 22:05:23

试试这个

#include <bits/stdc++.h>
using namespace std;
int dx[4]={-1,1,0,0};
int dy[4]={0,0,-1,1};
int a[1001][1001],n;
bool vis[1001][1001];
void dfs(int x,int y){
    if(x<0||x>n+1||y<0||y>n+1||vis[x][y]!=0) return ;
    vis[x][y]=1;
    for(int i=0;i<4;i++) dfs(x+dx[i],y+dy[i]);
}
signed main(){
    cin>>n;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            cin>>a[i][j];
            if(a[i][j]==0) vis[i][j]=0;
            else vis[i][j]=2;
        }
    }
    dfs(0,0);
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(vis[i][j]==0) cout<<2<<" ";
            else cout<<a[i][j]<<" ";
        }
        cout<<endl;
    }
    return 0;
} 

by first_king @ 2023-09-07 22:06:46

@One_JuRuo 对了，谢谢