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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. long long find_row(long long N) {
  5.  
  6.     long long left = 1;
  7.     long long right = N;
  8.     long long answer = -1;
  9.  
  10.     while (left <= right) {
  11.  
  12.         long long mid = left + (right - left) / 2;
  13.         long long total = mid * (mid + 1) / 2;
  14.  
  15.         if (total >= N) {
  16.             answer = mid;
  17.             right = mid - 1;
  18.         }
  19.         else {
  20.             left = mid + 1;
  21.         }
  22.     }
  23.  
  24.     return answer;
  25. }
  26.  
  27. int main() {
  28.  
  29.     ios_base::sync_with_stdio(false);
  30.     cin.tie(nullptr);
  31.  
  32.     int T;
  33.     cin >> T;
  34.  
  35.     while (T--) {
  36.  
  37.         long long N;
  38.         cin >> N;
  39.         cout << find_row(N) << '\n';
  40.     }
  41.  
  42.     return 0;
  43. }
Success #stdin #stdout 0.01s 5324KB
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https://ideone.com/GnQpcK
language:
C++14 (clang 8.0)
created:
9 days ago
visibility:
public

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