BZOJ 4591: [Shoi2015]超能粒子炮·改 lucas定理

https://www.lydsy.com/JudgeOnline/problem.php?id=4591

https://blog.csdn.net/qq_33229466/article/details/78827788 推导过程见该博客 

lucas定理就是  C(n,m)%p=C(n/p,m/p)*C(n%p,m%p)%p

其实还挺简单的但是我wa了好几次因为最开始算前缀和没有算从0中选x个数的这一行，惨。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<queue>
#include<bitset>
#include<queue>
using namespace std;
#define LL long long
const LL p=2333;
LL c[p+10][p+10]={},d[p+10][p+10]={};
LL lucas(LL x,LL k){
    if(x==0||k==0)return 1;
    return (lucas(x/p,k/p)*c[x%p+1][k%p+1])%p;
}
LL solve(LL x,LL k){
    if(k<0)return 0;
    return ((solve(x/p,k/p-1)*d[x%p+1][p])%p+(lucas(x/p,k/p)*d[x%p+1][k%p+1])%p)%p;
}
int main(){
    c[1][1]=1;for(int j=1;j<=2335;++j)d[1][j]=(d[1][j-1]+c[1][j])%p;
    for(int i=2;i<=2335;++i){
        for(int j=1;j<=i;++j)c[i][j]=(c[i-1][j]+c[i-1][j-1])%p;
        for(int j=1;j<=2335;++j)d[i][j]=(d[i][j-1]+c[i][j])%p;
    }
    int T;scanf("%d",&T);
    while(T-->0){
        LL x,k;
        scanf("%lld%lld",&x,&k);
        //if(k>x)k=x;
        printf("%lld
",solve(x,k));
    }
    return 0;
}