#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std ;
const int maxn = 100010 ;
int a[maxn] ;
int bit(int l , int r ,int num)
{
while(l <= r)
{
int mid = (l + r) >> 1;
if(a[mid] <= num)
l = mid + 1 ;
else
r = mid - 1 ;
}
return l;
}
int main()
{
int n ;int d ;
while(~scanf("%d%d" ,&n ,&d))
{
for(int i = 1;i <= n;i ++)
scanf("%d" ,&a[i]) ;
//cout<<bit(1 , n , 5)<<endl;
__int64 ans = 0;
for(int i = 1;i <= n - 2;i++)
{
int j = bit(i , n , a[i]+d) ;
if(j-i-2 > 0)
ans+=(__int64)(j-i-2)*(__int64)(j-i-1)/2;
}
printf("%I64d\n",ans) ;
}
return 0;
}
Codeforces Round #153 (Div. 1)APoints on Line
原文：http://blog.csdn.net/cq_pf/article/details/45315245
