Codeforces Round #153 (Div. 1), problem: (A) Points on Line solution

Codeforces Round #153 (Div. 1), problem: (A) Points on Line: http://codeforces.com/problemset/problem/251/A

Codeforces Round #153 (Div. 1), problem: (A) Points on Line editorial: http://codeforces.com/blog/entry/6054

Codeforces Round #153 (Div. 1), problem: (A) Points on Line solution: http://ideone.com/N2cHDh

#include <iostream>
#include <cstdio>
using namespace std;

int main() {
    int n, d, x[100005];
    long long int ans=0;
    scanf("%d%d", &n, &d);
    for(int i=0; i<n; i++) scanf("%d", x+i);
    for(int i=0, j=0; i<n; i++) {
        while(x[i]-x[j]>d) j++;
        ans+=(long long)(i-j)*(i-j-1)/2;
    }
    printf("%I64d", ans);
}

i tried the code below but it gave WA: http://ideone.com/e8VzQB

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <map>
using namespace std;

int main() {
    int n, d, x[100005], it;
    long long int cnt1, cnt2, tmp=-1, ans=0, ma=0, mi=0, dif=0;
    const int con=1e9+1;
    map <int, int> m;
    scanf("%d%d", &n, &d);
    for(int i=0; i<n; i++) scanf("%d", &x[i]);
    for(int i=1; i<n; i++) for(int j=x[i-1]; j<x[i]; j++) m[j]=i;
    m[x[n-1]]=n;
    for(int i=0; i<n; i++) {
        if(x[i]+d>=x[n-1]) it=x[n-1];
        else it=x[i]+d;
        dif=m[it]-m[x[i]]+1;
        if(dif>=3) {
            if(m[it]==tmp) continue;
            cnt1=1, cnt2=1;
            for(int j=1; j<=dif; j++) cnt1*=j;
            for(int j=1; j<=dif-3; j++) cnt2*=j;
            ans+=cnt1/(cnt2*6);
            tmp=m[it];
        }
    }
    printf("%I64d", ans);
    return 0;
}

note: if you give right AC approach similar to my WA approach, that would be appreciated