【题解】 bzoj2982: combination (Lucas定理)

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Solution

  • 板子题

Code

//It is coded by ning_mew on 7.25
#include<bits/stdc++.h>
#define LL long long
using namespace std;

const LL MOD=10007;

int T;
LL A[MOD],B[MOD],n,m;

void pre(){
	A[0]=B[0]=A[1]=B[1]=1;
	for(int i=2;i<MOD;i++)B[i]=-(MOD/i)*B[MOD%i]%MOD;
	for(int i=2;i<MOD;i++)A[i]=i*A[i-1]%MOD,B[i]=B[i]*B[i-1]%MOD;
	return;
}
LL C(LL n,LL m){
	if(m>n)return 0;
	return A[n]*B[n-m]%MOD*B[m]%MOD;
}
LL Lucas(LL n,LL m){
	if(m==0)return 1;
	return Lucas(n/MOD,m/MOD)*C(n%MOD,m%MOD)%MOD;
}
int main(){
	pre();
	scanf("%d",&T);
	for(int i=1;i<=T;i++){
		scanf("%lld%lld",&n,&m);
		printf("%lld\n",(Lucas(n,m)%MOD+MOD)%MOD);
	}return 0;
}

博主蒟蒻,随意转载。但必须附上原文链接:http://www.cnblogs.com/Ning-Mew/,否则你会场场比赛暴0!!!

posted @ 2018-08-25 19:31  Ning_Mew  阅读(205)  评论(0编辑  收藏  举报