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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long
  4. const int MAXN = 1e5 + 7;
  5. ll f[MAXN], n ,m, ans;
  6. vector <int> a[MAXN];
  7. bool mark[MAXN];
  8. void dfs(int u, int p){
  9.     mark[u] = 1;
  10.     for(auto v : a[u]){
  11.         if(!mark[v]) dfs(v, u);
  12.         if(v != p) f[u] = max(f[u], f[v] + 1);
  13.     }
  14. }
  15.  
  16. int main(){
  17.     ios_base::sync_with_stdio(0);
  18.     cout.tie(0);
  19.     cin.tie(0);
  20.     cin >> n >> m;
  21.     for(int i = 1; i <= m; i++){
  22.         int x, y;
  23.         cin >> x >> y;
  24.         a[x].push_back(y);
  25.         a[y].push_back(x);
  26.     }
  27.     dfs(1, -1);
  28.     for(int i = 1; i <= n; i++) ans = max(ans, f[i]);
  29.     cout << ans;
  30. }
Success #stdin #stdout 0.01s 6348KB
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https://ideone.com/kdmanI
language:
C++14 (gcc 8.3)
created:
3 days ago
visibility:
public

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