颜色填涂——过于水的bfs

 1 #include<queue>
 2 #include<cstdio>
 3 #include<iostream>
 4 using namespace std;
 5 const int N=32,ax[]={1,-1,0,0},ay[]={0,0,1,-1};
 6 struct node{int x,y;};
 7 int n,cnt=1,col[N][N];
 8 bool gr[N][N],vis[N][N],out[N];
 9 void bfs(int sx,int sy){
10     queue<node> q;
11     q.push((node){sx,sy});
12     vis[sx][sy]=true;
13     col[sx][sy]=cnt;
14     while(!q.empty()){
15         node now=q.front();q.pop();
16         for(int i=0;i<4;i++){
17             int nx=ax[i]+now.x,ny=ay[i]+now.y;
18             if(vis[nx][ny]||nx>n||ny>n||nx<1||ny<1||gr[nx][ny]!=gr[sx][sy])
19                 continue;
20             if(nx==1||ny==1||nx==n||ny==n)out[cnt]=true;
21             col[nx][ny]=cnt;
22             vis[nx][ny]=true;
23             q.push((node){nx,ny});
24         }
25     }
26 }
27 int main(){
28     freopen("zenith.txt","r",stdin);
29     cin>>n;
30     for(int i=1;i<=n;i++)
31         for(int j=1;j<=n;j++)
32             cin>>gr[i][j];
33     for(int i=1;i<=n;i++)
34         for(int j=1;j<=n;j++)
35             if(!vis[i][j]&&!gr[i][j]){
36                 bfs(i,j);
37                 cnt++;
38             }
39     for(int i=1;i<=n;i++){
40         for(int j=1;j<=n;j++)
41             if(out[col[i][j]]||gr[i][j])cout<<gr[i][j]<<" ";
42             else cout<<2<<" ";
43         cout<<endl;
44     }
45     return 0;
46 }