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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. #define ll long long
  5. #define ul unsigned long long
  6.  
  7. ll mod = 1e9+7;
  8. const int N = 1e5+5;
  9. int MOD = 998244353;
  10. int bit[200000];
  11. int n, m;
  12. int dem = 0;
  13. vector<int> adj[N];
  14. bool visit[N];
  15. void nhap(){
  16. 	cin >> n >> m;
  17. 	int x,y;
  18. 	for(int i= 0 ; i < m ;  i++){
  19. 		cin >> x >> y;
  20. 		adj[x].push_back(y);
  21. 		adj[y].push_back(x);
  22. 	}
  23. }
  24. void bfs(int s) { 
  25.  
  26.     dem++;
  27.  
  28.     queue <int> q;
  29.     q.push(s);
  30.     visit[s] = true;
  31.     while (!q.empty()) {
  32.         int u = q.front();
  33.         q.pop();
  34.         for (int v : adj[u]) {
  35.             if (!visit[v]) {
  36.                 visit[v] = true;
  37.                 q.push(v);
  38.             }
  39.         }
  40.     }
  41. }
  42. int main() {
  43. 	//freopen("CSBN.INP", "r", stdin);
  44. 	//freopen("CSBN.OUT", "w", stdout);
  45. 	ios_base::sync_with_stdio(0);
  46. 	cin.tie(0);
  47. 	cout.tie(0);
  48.     nhap();
  49.     for(int i=1; i<= n ; i++){
  50.     	if(!visit[i]){
  51.     		bfs(i);
  52. 		}
  53. 	}
  54. 	cout << dem;
  55.  
  56. }
  57.  
Success #stdin #stdout 0.01s 5780KB
comments (?)
stdin
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7 6
1 2
1 3
2 3
5 6
6 7
5 7
stdout
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3
https://ideone.com/rSDSzS
language:
C++14 (clang 8.0)
created:
7 days ago
visibility:
public

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