bzoj2982: combination

Posted 2020-08-25 Bloodline

Lucas定理模版题

T行，每行一个数，为C(n, m) mod 10007的答案。

 

 1 #include<bits/stdc++.h>
 2 #define rep(i,l,r) for(int i=l;i<=r;++i)
 3 using namespace std;
 4 typedef long long ll;
 5 const ll p=10007;
 6 ll n,m,T;
 7 ll Pow(int x,int y){
 8     if(!y)return 1;
 9     ll t=Pow(x,y/2)%p; (t*=t)%=p;
10     if(y&1)return t*x;else return t;
11 }
12 ll c(ll n,ll m){
13     if(n<m)return 0;
14     ll ans=1;
15     rep(i,1,m){
16         ans=ans*(((n-m+i)%p)*Pow(i,p-2)%p)%p;  
17     }
18     return ans;
19 }
20 ll lucas(ll n,ll m){
21     if(!m)return 1;
22     return lucas(n/p,m/p)*c(n%p,m%p)%p;
23 }
24 int main(){
25     cin>>T;
26     while(T--){
27         cin>>n>>m;
28         cout<<lucas(n,m)<<endl;
29     }
30 }

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