Submission #833638

#	Time	Username	Problem	Language	Result	Execution time	Memory
833638		tolbi	Rack (eJOI19_rack)	C++17	100 / 100	3 ms	276 KiB

rack

#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9+7;
#define tol(bi) (1LL<<((int)(bi)))
int fpow(int base, int pow){
	int rval = 1;
	while (pow){
		if (pow&1){
			rval=(((long long)rval*base)%MOD);
		}
		base=(((long long)base*base)%MOD);
		pow>>=1;
	}
	return rval;
}
int solve(int n, long long k){
	if (n<=64 && k>tol(n-1)){
		return ((long long)solve(n-1,k-tol(n-1))*2ll)%MOD;
	}
	else {
		if (k==1){
			return 1ll;
		}
		if (k%2){
			return solve(n-1,k/2+1);
		}
		else {
			return ((long long)solve(n-1,k/2)+fpow(2,n-1))%MOD;
		}
	}
}
int main(){
	long long n,k;
	cin>>n>>k;
	cout<<solve(n,k)<<endl;
}

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