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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4. const int MOD1 = 1e9 + 7;
  5. using ll  =  long long;
  6. #define optimize()    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  7.  
  8. ll ceildiv(ll a, ll b){return 1LL * (a + b - 1) / b;}
  9.  
  10. ll n, x;
  11. const int N = 1e5 + 5;
  12. struct minion { ll a, h; };
  13. minion a[N];
  14.  
  15. void Input() {
  16.     cin >> n >> x;
  17.     for(int i = 0; i < n; i++)
  18.         cin >> a[i].a >> a[i].h,
  19.         a[i].h = ceildiv(a[i].h, x);
  20. }
  21.  
  22. void Solve() {
  23.     sort(a, a + n, [&](minion a, minion b){ return a.a * b.h > a.h * b.a; });
  24.     ll curr = 0;
  25.     ll res = 0;
  26.     for(int i = 0; i < n; i++) {
  27.         curr += a[i].h;
  28.         curr %= MOD1;
  29.         res += curr * a[i].a;
  30.         res %= MOD1;
  31.     }
  32.     cout << (res + 1) % MOD1 << "\n";
  33. }
  34.  
  35. int main()
  36. {
  37.     optimize();
  38.     Input();
  39.     Solve();
  40.     return 0;
  41. }
  42.  
Success #stdin #stdout 0.01s 5448KB
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https://ideone.com/PJPG87
language:
C++ (gcc 8.3)
created:
1 year ago
visibility:
secret

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