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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. int n,m;
  4. struct Node
  5. {
  6. 	int v;
  7. 	int id;
  8. };
  9. vector<vector<Node>> inp;
  10. vector<int> low, num;
  11. vector<bool>joint;
  12. vector<bool> vis;
  13. vector<int>dp;
  14. stack<pair<int, int>> st;
  15. int times = 0;
  16. int ans = 0;
  17. void dfs(int u, int par)
  18. {
  19. 	low[u] = num[u] = ++times;
  20. 	int child = 0;
  21. 	unordered_set<int> sett;
  22. 	for(Node v: inp[u])
  23. 	{
  24. 		int x = v.v;
  25. 		int id = v.id;
  26. 		int minx = min(u, x);
  27. 		int maxx = max(u, x);
  28. 		if(id == par) continue;
  29. 		if(num[x] == 0)
  30. 		{
  31. 			st.push({minx, maxx});
  32. 			dfs(x, id);
  33.  
  34. 			low[u] = min(low[u], low[x]);
  35. 			child++;
  36. 			if(low[x] >= num[u])
  37. 			{
  38.  
  39. 				while(st.top().first != minx || st.top().second != maxx)
  40. 				{
  41.  
  42. 					sett.insert(st.top().first);
  43. 					sett.insert(st.top().second);
  44. 					st.pop();
  45. 				}
  46. 				st.pop();
  47. 				ans = max(ans, (int)sett.size());
  48. 			}
  49. 		}
  50. 		else if(num[x] < num[u]) { st.push({minx, maxx}); low[u] = min(low[u], num[x]); }
  51. 	}
  52. 	return;
  53. }
  54.  
  55.  
  56. int main()
  57. {
  58. 	ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
  59. 	cin >> n >> m;
  60. 	inp.resize(n+1);
  61. 	low.resize(n+1);
  62. 	num.resize(n+1);
  63. 	joint.resize(n+1);
  64. 	for(int i =1; i<=m; i++)
  65. 	{
  66. 		int a,b; cin >> a >> b;
  67. 		inp[a].push_back({b, i});
  68. 		inp[b].push_back({a, i});
  69. 	}
  70.  
  71. 	for(int i =1; i<=n; i++) if(num[i] == 0) dfs(i, -1);
  72. 	cout << ans;
  73.  
  74. 	return 0;
  75. }
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin
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13 12
1 12
3 4
4 13
4 6
12 13
8 13
6 13
1 13
5 10
5 6
6 10
4 8
stdout
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4
https://ideone.com/zuvUcm
language:
C++ (gcc 8.3)
created:
5 hours ago
visibility:
public

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