Submission #440386

#	Time	Username	Problem	Language	Result	Execution time	Memory
440386		stoyan_malinin	Rack (eJOI19_rack)	C++14	100 / 100	1 ms	204 KiB

rack

#include <iostream>
#include <vector>
#include <queue>
#include <set>

using namespace std;

const long long mod = 1e9 + 7;

long long fastPow(long long x, long long p)
{
    long long ans = 1, curr = x;

    while(p!=0)
    {
        if(p%2!=0) ans = (ans*curr)%mod;

        p/=2;
        curr = (curr*curr)%mod;
    }

    return ans;
}
long long revBits(long long x, int bitCnt)
{
    long long res = 0;
    for(int bit = 0;bit<min(bitCnt, 63);bit++)
    {
        if(((x>>bit)&1)==1)
            res = (res + fastPow(2, bitCnt-bit-1))%mod;
    }

    return res;
}

int main()
{
    long long n, k;
    cin >> n >> k;

    cout << (revBits(k-1, n) + 1)%mod << '\n';
}
/*
5 3
5 0 1 2 5
5 2 3
4 2 3
1 4 5

3 1
2 2 1
1 2 3
*/

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