fork download
copy 
  1. #include <bits/stdc++.h>
  2. #define int long long
  3. using namespace std;
  4. int n,ans=0,bit[100005];
  5. pair <int,int> p[100005];
  6. void UPDATE(int i, int v)
  7. {
  8.     while (i<=n) bit[i]+=v,i+=i&(-i);
  9.     return;
  10. }
  11. int GET(int l, int r)
  12. {
  13.     l--;
  14.     int resl=0,resr=0;
  15.     while (l>0) resl+=bit[l],l-=l&(-l);
  16.     while (r>0) resr+=bit[r],r-=r&(-r);
  17.     return resr-resl;
  18. }
  19. signed main()
  20. {
  21.     ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
  22.     cin>>n;
  23.     for (int i=1;i<=n;i++) cin>>p[i].first,p[i].second=i;
  24.     sort(p+1,p+n+1,greater<pair<int,int>>());
  25.     for (int i=1;i<=n;i++)
  26.     {
  27.         UPDATE(p[i].second,1);
  28.         ans+=GET(1,p[i].second-1);
  29.     }
  30.     cout<<ans<<'\n';
  31.     return 0;
  32. }
  33.  
Success #stdin #stdout 0s 5308KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
0
https://ideone.com/LLNoTB
language:
C++14 (gcc 8.3)
created:
2 days ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!