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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. const int N=1e6+5;
  4. long long a[N];
  5. long n;
  6. long long s=0,m,l=0;
  7. long long tknp(long long a[],long long dau,long long cuoi,long long k)
  8. {
  9.     long long res=-1;
  10.     while(dau<=cuoi)
  11.     {
  12.         long long giua=(dau+cuoi)/2;
  13.         if(a[giua]>k)
  14.         {
  15.             res=giua;
  16.             cuoi=giua-1;
  17.         }
  18.         else dau=giua+1;
  19.     }
  20.     return res;
  21. }
  22. int main()
  23. {
  24.     cin>>n>>m;
  25.     for(int i=1;i<=n;i++) cin>>a[i];
  26.     sort(a+1,a+n+1);
  27.     for(int i=1;i<=n;i++)
  28.     {
  29.         l=tknp(a,i+1,n,m-a[i]);
  30.         if(l!=-1) s=s+n-l+1;
  31.     }
  32.     cout<<s;
  33. }
  34.  
Success #stdin #stdout 0.01s 5408KB
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Standard output is empty
https://ideone.com/uAeJTm
language:
C++14 (gcc 8.3)
created:
1 year ago
visibility:
public

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