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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. typedef long long ll;
  5.  
  6. int main() {
  7.     ll t;
  8.     cin >> t;
  9.  
  10.     while (t--) {
  11.         ll n;
  12.         cin >> n;
  13.  
  14.         vector<ll> G[n + 1];
  15.  
  16.         for (int i = 1; i <= n - 1; i++) {
  17.             ll y;
  18.             cin >> y;
  19.             G[y].push_back(i);
  20.         }
  21.  
  22.         vector<ll> l, r;
  23.  
  24.         for (int i = 1; i <= n; i++) {
  25.             if (G[i].size() > 0)
  26.                 l.push_back(G[i].size());
  27.         }
  28.  
  29.         l.push_back(1);
  30.         sort(l.begin(), l.end(), greater<ll>());
  31.  
  32.         ll c = 0;
  33.  
  34.         // FIRST STAGE
  35.         while (!l.empty()) {
  36.             sort(l.begin(), l.end(), greater<ll>());
  37.  
  38.             // decrease all r by 1
  39.             vector<ll> r1;
  40.             for (ll x : r) {
  41.                 if (x - 1 > 0) r1.push_back(x - 1);
  42.             }
  43.             r = r1;
  44.  
  45.             c++;
  46.  
  47.             ll largest = l[0];
  48.             l.erase(l.begin());
  49.  
  50.             if (largest - 1 > 0)
  51.                 r.push_back(largest - 1);
  52.         }
  53.  
  54.         // SECOND STAGE
  55.         while (!r.empty()) {
  56.  
  57.             vector<ll> r1;
  58.             for (ll x : r) {
  59.                 if (x - 1 > 0) r1.push_back(x - 1);
  60.             }
  61.             r = r1;
  62.  
  63.             c++;
  64.  
  65.             if (!r.empty()) {
  66.                 sort(r.begin(), r.end(), greater<ll>());
  67.                 r[0]--;
  68.                 if (r[0] == 0) r.erase(r.begin());
  69.             }
  70.         }
  71.  
  72.         cout << c << endl;
  73.     }
  74.  
  75.     return 0;
  76. }
  77.  
Success #stdin #stdout 0s 5304KB
comments (?)
stdin
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5
7
1 1 1 2 2 4
5
5 5 1 4
2
1
3
3 1
6
1 1 1 1 1
stdout
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4
4
2
3
4
https://ideone.com/DnUSsY
language:
C++14 (gcc 8.3)
created:
3 days ago
visibility:
public

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