Lucas模板&快速幂模板

/* ***********************************************
Author        :guanjun
Created Time  :2016/5/20 0:28:36
File Name     :hdu5698.cpp
************************************************ */
#include <iostream>
#include <cstdlib>
#include <stdio.h>
#include <set>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#define ll long long
#define MOD 1000000007
#define INF 0x3f3f3f3f
#define maxn 200010
using namespace std;

ll fac[maxn],inv[maxn];
ll Pow(ll a,ll n,ll m){
ll ans=1;
while(n) {
if(n&1) {
ans*=a;
ans%=m;
}
a=a*a%m;
n>>=1;
}
return ans;
}
ll C(ll n,ll m,ll p){
ll res=1;
while(n&&m){
ll a=n%p;
ll b=m%p;
if(a<b)return 0;
res=res*fac[a]%p*Pow(fac[b]*fac[a-b]%p,p-2,p)%p;
n/=p;
m/=p;
}
return res;
}

void init(){
fac[0]=1;
inv[0]=1;
for(int i=1;i<=maxn;i++){
fac[i]=fac[i-1]*i%MOD;
inv[i]=Pow(fac[i],MOD-2,MOD);//费马小定理，要求MOD为素数
}
}
int main()
{
init();
ll n,m;
while(cin>>n>>m){
printf("%I64d\n",C(n,m,MOD));
}
return 0;
}