HDU 3037 Saving Beans （Lucas定理）

#include <iostream>
#include <cstring>
#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <vector>
#include <queue>
#include <map>
using namespace std;
#define LL long long
#define ULL unsigned long long
#define del(a,b) memset(a,b,sizeof(a))
#define PI 3.14159265358
const int INF=99999999;
ULL exp_mod(ULL a,ULL b,ULL p){
    ULL res=1;
    while(b!=0){
        if(b&1)res=(res*a)%p;
        a=(a*a)%p;
        b>>=1;
    }
    return res;
}
ULL Comb(ULL a,ULL b,ULL p){
    if(a<b)return 0;
    if(a==b)return 1;
    if(b>a-b)b=a-b;
    LL ans=1,ca=1,cb=1;
    for(LL i=0;i<b;i++){
        ca=(ca*(a-i))%p;
        cb=(cb*(b-i))%p;
    }
    ans=(ca*exp_mod(cb,p-2,p))%p;
    return ans;
}
ULL Lucas(ULL n,ULL m,int p){
    ULL ans=1;
    while(n&&m&&ans){
        ans=(ans*Comb(n%p,m%p,p))%p;
        n/=p;
        m/=p;
    }
    return ans;
}
int T,P;
LL N,M;
int main(){
    scanf("%d",&T);
    while(T--){
        scanf("%lld%lld%d",&N,&M,&P);
        printf("%lld\n",Lucas(N+M,M,P));
    }
}