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  1. #include <bits/stdc++.h>
  2. #define fi first
  3. #define se second
  4. #define ll long long
  5. #define el <<"\n"
  6. #define pll pair< ll, ll >
  7. #define pb push_back
  8. using namespace std;
  9. long long n, d[100009];
  10. vector< ll > a[100009];
  11. void dfs(ll k, ll cha){
  12.     bool kt = 0;
  13.     ll res = -2, sl;
  14.     for(ll i : a[k])
  15.         if(i != cha){
  16.             kt = 1;
  17.             dfs(i, k);
  18.             if(res == d[i])
  19.                 sl++;
  20.             if(res < d[i]){
  21.                 res = d[i];
  22.                 sl = 1;
  23.  
  24.             }
  25.         }
  26.     if(!kt){
  27.         d[k] = 0;
  28.         return;
  29.     }
  30.     if(sl > 1)
  31.         d[k] = res + 1;
  32.     else
  33.         d[k] = res;
  34.  
  35. }
  36. void lm(){
  37.     ll i;
  38.     dfs(1, 0);
  39.     cout << d[1] el;
  40. }
  41. int main()
  42. {
  43.     ios_base::sync_with_stdio(false);
  44.     cin.tie(NULL);cout.tie(NULL);
  45.  
  46.     freopen("PINETREE.inp","r",stdin);
  47.     freopen("PINETREE.out","w",stdout);
  48. ///------- MINH KHANG ----------///
  49.     ll i;
  50.     cin >> n;
  51.     for(i = 1; i < n ;++i){
  52.         ll x, y;
  53.         cin >> x >> y;
  54.         a[x].pb(y);
  55.         a[y].pb(x);
  56.     }
  57.     lm();
  58.     return 0;
  59. }
  60.  
Success #stdin #stdout 0.01s 6760KB
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https://ideone.com/Cipc43
language:
C++ (gcc 8.3)
created:
12 days ago
visibility:
public

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