Submission #237605

#	Time	Username	Problem	Language	Result	Execution time	Memory
237605		Pbezz	Rack (eJOI19_rack)	C++14	40 / 100	5 ms	384 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){

ll res=1;
	while(exp>0){

	if(exp%2==1){

	exp--; res*=base;
	res%=MOD;
	base%=MOD;

	}
	if(exp==0)break;

	base*=base; base%=MOD;
	exp/=2;

	}

	return res;

}

ll solve(ll n, ll k){

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

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

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


}


int main(){

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

	ans=solve(n,k);
	if(ans<0)ans+=MOD;
	cout<<ans<<'\n';

return 0; 
}

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 0 / 60