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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define int long long
  4.  
  5. int f(int k, int m) {
  6.     if (m <= k) {
  7.         return m * (m + 1) / 2;
  8.     }
  9.     int A = k * (k + 1) / 2;
  10.  
  11.     int r = m - k;          
  12.     int B = r * (2 * k - r + 1) / 2;
  13.  
  14.     return A + B;
  15. }
  16.  
  17. void solve() {
  18.     int k, x;
  19.     cin >> k >> x;
  20.  
  21.     int l = 1, r = 2 * k, ans = r;
  22.  
  23.     while (l <= r) {
  24.         int m = (l + r) / 2;
  25.  
  26.         if (f(k, m) >= x) {
  27.             ans = m;
  28.             r = m - 1;
  29.         } else {
  30.             l = m + 1;
  31.         }
  32.     }
  33.  
  34.     cout << ans << "\n";
  35. }
  36.  
  37. int32_t main() {
  38.     ios::sync_with_stdio(false);
  39.     cin.tie(nullptr);
  40.  
  41.     int t;
  42.     cin >> t;
  43.     while (t--) solve();
  44. }
  45.  
Success #stdin #stdout 0.01s 5308KB
comments (?)
stdin
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7
4 6
4 7
1 2
3 7
2 5
100 1
1000000000 923456789987654321
stdout
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3
4
2
4
3
1
1608737401
https://ideone.com/YLdBOd
language:
C++ (gcc 8.3)
created:
3 days ago
visibility:
public

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