Submission #19550

#	Time	Username	Problem	Language	Result	Execution time	Memory
19550		Namnamseo	Ω (kriii4_P3)	C++14	0 / 100	0 ms	1084 KiB

P3

#include <cstdio>
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()
{
    int p,q,n,k;
    scanf("%d%d%d%d",&p,&q,&n,&k);
    if(q==0){
        if(k==0) puts("0");
        else puts("1");
        return 0;
    } else if(p==q){
        if(k==n) puts("1");
        else puts("0");
        return 0;
    }
    if(n==k){
        puts("1");
        return 0;
    }
    ll bunja = (pow(p-q,n) - pow(q,k) * pow(p-q, n-k)%M + M)%M;
    ll bunmo = (pow(p-q,n) - pow(q,n) + M)%M;
    printf("%d\n",int( bunja*pow(bunmo,M-2)%M ));
    return 0;
}

• Subtask 1: 0 / 100