【HDU3037】Saving Beans

Lucas的裸题，学习一个。

#include<bits/stdc++.h>
#define N 100010
using namespace std;
typedef long long ll;
ll a[N];
int p;
ll pow(ll y,int z,int p){
    y%=p;ll ans=;
    for(int i=z;i;i>>=,y=y*y%p)if(i&)ans=ans*y%p;
    return ans;
}
ll C(ll n,ll m){
    if(m>n)return ;
    return ((a[n]*pow(a[m],p-,p))%p*pow(a[n-m],p-,p)%p);
}
ll Lucas(ll n,ll m){
    if(!m)return ;
    return C(n%p,m%p)*Lucas(n/p,m/p)%p;
}
inline int read(){
    int f=,x=;char ch;
    do{ch=getchar();if(ch=='-')f=-;}while(ch<''||ch>'');
    do{x=x*+ch-'';ch=getchar();}while(ch>=''&&ch<='');
    return f*x;
}
int main(){
    int T=read();
    while(T--){
        int n=read(),m=read();p=read();
        a[]=;
        for(int i=;i<=p;i++)a[i]=(a[i-]*i)%p;
        cout<<Lucas(n+m,n)<<endl;
    }
}