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=1; for(int i=z;i;i>>=1,y=y*y%p)if(i&1)ans=ans*y%p; return ans; } ll C(ll n,ll m){ if(m>n)return 0; return ((a[n]*pow(a[m],p-2,p))%p*pow(a[n-m],p-2,p)%p); } ll Lucas(ll n,ll m){ if(!m)return 1; return C(n%p,m%p)*Lucas(n/p,m/p)%p; } inline int read(){ int f=1,x=0;char ch; do{ch=getchar();if(ch=='-')f=-1;}while(ch<'0'||ch>'9'); do{x=x*10+ch-'0';ch=getchar();}while(ch>='0'&&ch<='9'); return f*x; } int main(){ int T=read(); while(T--){ int n=read(),m=read();p=read(); a[0]=1; for(int i=1;i<=p;i++)a[i]=(a[i-1]*i)%p; cout<<Lucas(n+m,n)<<endl; } }