题解与来源题共享。已有题解默认通过；新增或编辑后需由来源域管理员审核。待审核、驳回题解仅作者和审核管理员可见。来源域：system

• 1

  Asuka LV 7 @ 2026-5-28 15:01:38

  #include<bits/stdc++.h>
  using namespace std;
  typedef long long ll;
  const int N = 510;
  int g[N][N];
  bool vis[N][N];
  int n;
  const int dx[] = {-1,0,1,0};
  const int dy[] = {0,1,0,-1};
  
  void bfs(int x,int y){
  	queue<pair<int,int>> q;
  	q.push({x,y});
  	vis[x][y] = true;
  	
  	while(!q.empty()){
  		auto it = q.front();
  		q.pop();
  		int xx = it.first,yy = it.second;
  		
  		for(int i=0;i<4;i++){
  			int nx = xx + dx[i],ny = yy + dy[i];
  			if(nx>=1&&nx<=n&&ny>=1&&ny<=n){
  				if(!vis[nx][ny]&&g[nx][ny]==1){
  					vis[nx][ny] = true;
  					q.push({nx,ny});
  				}
  			}
  		}
  	}
  }
  
  int main() {
      ios::sync_with_stdio(false);
      cin.tie(0);
  
  	cin>>n;
  	for(int i=1;i<=n;i++){
  		for(int j=1;j<=n;j++){
  			cin>>g[i][j];
  		}
  	}
      int res=0;
      for(int i=1;i<=n;i++){
  		for(int j=1;j<=n;j++){
  			if(!vis[i][j]&&g[i][j]==1){
  				bfs(i,j);
  				res++;
  			}
  		}
  	}
      cout<<res;
      return 0;
  }