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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. #define fast_io ios::sync_with_stdio(false); cin.tie(NULL)
  5. #define int long long
  6.  
  7. void solve() {
  8.     int n;
  9.     cin >> n;
  10.  
  11.     vector<int> a(n+1), pref(n+1,0);
  12.     for (int i = 1; i <= n; i++) {
  13.         cin >> a[i];
  14.         pref[i] = pref[i-1] + a[i];
  15.     }
  16.  
  17.     int original = pref[n];
  18.     int best_gain = 0;
  19.  
  20.     long long bestB = LLONG_MAX;
  21.  
  22.     for (int r = 1; r <= n; r++) {
  23.  
  24.         long long B_r = 1LL*r*r - r - pref[r-1];
  25.         bestB = min(bestB, B_r);
  26.  
  27.         long long A_r = 1LL*r*r + r - pref[r];
  28.  
  29.         long long gain = A_r + bestB;
  30.  
  31.         best_gain = max(best_gain, gain);
  32.     }
  33.  
  34.     cout << original + best_gain << "\n";
  35. }
  36.  
  37. int32_t main(){
  38.     fast_io;
  39.     int t;
  40.     cin >> t;
  41.     while(t--) solve();
  42. }
  43.  
Success #stdin #stdout 0.01s 5328KB
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https://ideone.com/mYrcI3
language:
C++ (gcc 8.3)
created:
23 hours ago
visibility:
public

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