제출 #237607

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
237607		Pbezz	Rack (eJOI19_rack)	C++14	100 / 100	203 ms	30840 KiB

rack

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define MOD 1000000007
#define MAXN 100005
typedef pair<int, int> pii;

ll fast(ll base, ll exp){

	if(exp==0) return 1%MOD;

	ll u = fast(base,exp/2); 

	u=(u*u)%MOD;

	if (exp%2==1) u=(u*base)%MOD;

	return u; 
}


ll solve(ll n, ll k){

	if(n==1&&k==1)return 1%MOD;
	if(n==1&&k==2)return 2%MOD;

	ll ans = fast(2,n-1);

	if(k%2==0)return (solve(n-1,k/2)+ans)%MOD;
	else return solve(n-1,(k+1)/2)%MOD;


}


int main(){

	ll n,k,ans;
	cin>>n>>k; 

	ans=solve(n,k)%MOD;

	if(ans<0)ans+=MOD;

	cout<<ans<<'\n';

return 0; 
}

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 60 / 60