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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. typedef long long int ll;
  4.  
  5. int main() {
  6.     ll n;
  7.     cin>>n;
  8.     ll k;cin>>k;
  9.     ll b[n];
  10.     for(ll i=0;i<n;i++){
  11.         cin>>b[i];
  12.     }
  13.     ll c = 0;
  14.  
  15.  
  16.     sort(b,b+n);
  17.     ll i=0,j=n-1;
  18.     while(i<j){
  19.     	if(b[i]+b[j]>k){
  20.     		j--;
  21.     	}else{
  22.     		c+=(j-i);
  23.     		i++;
  24.     	}
  25.     }
  26.     cout<<c;
  27.     return 0;
  28. }//RRRRR
Success #stdin #stdout 0.01s 5280KB
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https://ideone.com/qM53m8
language:
C++ (gcc 8.3)
created:
5 days ago
visibility:
public

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