Submission #19641

#	Time	Username	Problem	Language	Result	Execution time	Memory
19641		Namnamseo	Ω (kriii4_P3)	C++14	100 / 100	0 ms	1720 KiB

P3

#include <iostream>
using namespace std;
typedef long long ll;
const int M=int(1e9)+7;
ll pow(ll a,ll b){
    if(b==0) return 1;
    ll ret=pow(a,b/2);
    ret=(ret*ret)%M;
    if(b&1) ret=(ret*a)%M;
    return ret;
}
int main()
{
    ll p,q,n,k;
    cin>>p>>q>>n>>k;
    if(k==0){ cout<<0; return 0; }
    if(k==n){ cout<<1; return 0; }
    if(q==0){
        cout<<1;
        return 0;
    } else if(p==q){
        cout<<0;
        return 0;
    } else if(p == 2*q){
        cout<<(k*pow(n,M-2))%M;
        return 0;
    }
    int rja=q, rmo=p-q;
    ll r=rja*pow(rmo,M-2)%M;
    ll bunja = (M + 1 - pow(r,k))%M;
    ll bunmo = (M + 1 - pow(r,n))%M;
    cout<<(bunja*pow(bunmo,M-2)%M);
    return 0;
}

• Subtask 1: 100 / 100