ZCO-2014::Variation

 

#include <bits/stdc++.h>
using namespace std ;
#define boost ios::sync_with_stdio(false);cin.tie(0)

int main (){
    int n ,k ;
    cin >> n >> k ;
    int arr[n];
    for (int i = 0; i < n; ++i) {
        cin >> arr[i];

    }
    int count{0};
    int i = 0 ;
    int j = 0 ;
    sort(arr,arr + n);
    while (j < n){
        if (arr[j] - arr[i] >= k){
            count += n-j;
            i++ ;
        } else{
            j++;
        }
    }
    cout << count << '\n';

    return 0;
}