CF1833F Ira and Flamenco

:::数组溢出 可以用map

:::前缀和优化

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<map>
//#include<queue>
//#include<vector>
//#include<bits/stdc++.h>
#define ll long long
#define ddd printf("-----------------------\n");
using namespace std;
const int maxn=2e5+10 ;
const int mod=1e9+7;

int n,m,a[maxn],res,sum[maxn];
map<int,int> mp;

int ksm(int a,int b)
{
    int res=1;
    while(b)
    {
        if(b%2==1)    res=1ll*res*a%mod;
        a=1ll*a*a%mod;
        b>>=1;
    }
    return res%mod;
}
/*
int ksm(int a, int k) {
    int ret = 1;
    while (k) {
        if (k & 1) ret = 1ll * ret * a % mod;
        a = 1ll * a * a % mod;
        k >>= 1;
    }
    return ret;
}*/


int main()
{
    ios::sync_with_stdio(false);
    int T;cin>>T;
    while(T--)
    {
        res=0,sum[0]=1;mp.clear();
         
        cin>>n>>m;
        for(int i=1;i<=n;i++) cin>>a[i],mp[a[i]]++;
        sort(a+1,a+n+1); 
        int len=unique(a+1,a+n+1)-(a+1);
        
        //int pr=1;
        for(int i=1,j=1;i<=len;i++)
        {
            sum[i]=1ll*sum[i-1]*mp[a[i]]%mod;
            if(a[i]-a[j]>=m) j++;
            if(i-j+1==m&&a[i]-a[j]==m-1){
                int tmp=1ll*sum[i]*ksm(sum[j-1],mod-2)%mod;
                res=(res+tmp)%mod;
            } 
        }
        
        cout<<res<<'\n';
    } 
    
    return 0;
}