luogu P1162 填涂颜色

https://www.luogu.org/problem/show?pid=1162

//其实很简单的吧

//就是最外圈加一圈0 ，然后把外圈里面的0都遍历了

//剩下的0 就变成2 就行了

#include<bits/stdc++.h>

using namespace std;

typedef pair <int,int> pii;

int n ,s[][];

bool vis[][];

int fx[]={-,,,};

int fy[]={,-,,};

bool check(int x,int y)

{

    if(!vis[x][y] && s[x][y] ==  && x>= && x<=n+ && y>= && y<=n+)

        return ;

    return ;

}

void bfs(int x,int y)

{

    queue<pii > que;

    que.push({x,y});

    //cout<<"yes1"<<endl;

    while (que.size() )

    {

        pii now = que.front(); que.pop();

        if( vis[now.first][now.second] )

            continue;

        vis[now.first][now.second] = ;//注意该点已经访问过   这里很容易忘记的吧

        //cout<<"yes2"<<endl;

        for(int i=;i<;i++)

        {

            //cout<<"yes3"<<endl;

            int dx= now.first+fx[i];

            int dy= now.second+fy[i];

            if(check(dx,dy))

            {

                //cout<<"yes3"<<endl;

                que.push({dx,dy});

            }

        }

    }

}

int main ()

{

    scanf("%d",&n);

    for(int i=;i<=n;i++)

        for(int j=;j<=n;j++)

            scanf("%d",&s[i][j]);

    //cout<<endl;

    //因为外圈已经本身就是0了

    //从第0行到第n+1行

    bfs(,);

    for(int i=;i<=n;i++)

    {

        for(int j=;j<=n;j++)

        {

            if( vis[i][j] )

                cout<<<<" ";

            else if(s[i][j] == )

                cout<<<<" ";

            else

                cout<<<<" ";

        }

        cout<<endl;

    }

}