oj.uz

Submission #439724

# Submission time Handle Problem Language Result Execution time Memory
439724 2021-06-30T16:17:35 Z stoyan_malinin Rack (eJOI19_rack) C++14
100 / 100
 5 ms 292 KB 
#include <iostream>

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 walkLeft(long long node, int layer, int n)
{
    if(layer==n+1) return node%mod;
    return walkLeft((node*2)%mod, layer+1, n);
}

long long revNum(long long x, int bitCnt)
{
    long long res = 0;
    for(int bit = 0;bit<bitCnt;bit++)
        res += (((x>>bit)&1)<<(bitCnt-bit-1));
    
    return res;
}

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

    if(k==1)
    {
        cout << "1" << '\n';
        return 0;
    }
    k--;

    int layer;
    for(layer = 1;layer<=n;layer++)
    {
        long long maxNum = (1LL<<(layer)) - 1;
        if(k<=maxNum) break;
    }   

    long long start = (1LL<<(layer-1));
    long long kLeft = k - ((1LL<<(layer-1)) - 1) - 1;
    long long node = start + revNum(kLeft, layer-1);

    node %= mod;
    cout << (walkLeft(node*2+1, layer+1, n) - fastPow(2, n) + 1 + mod)%mod << '\n';
}

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB Output is correct
2 Correct 1 ms 204 KB Output is correct
3 Correct 1 ms 204 KB Output is correct
4 Correct 1 ms 216 KB Output is correct
5 Correct 0 ms 204 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB Output is correct
2 Correct 1 ms 204 KB Output is correct
3 Correct 1 ms 204 KB Output is correct
4 Correct 1 ms 216 KB Output is correct
5 Correct 0 ms 204 KB Output is correct
6 Correct 1 ms 204 KB Output is correct
7 Correct 1 ms 204 KB Output is correct
8 Correct 1 ms 204 KB Output is correct
9 Correct 0 ms 204 KB Output is correct
10 Correct 1 ms 204 KB Output is correct

Subtask #3
60.0 / 60.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB Output is correct
2 Correct 1 ms 204 KB Output is correct
3 Correct 1 ms 204 KB Output is correct
4 Correct 1 ms 216 KB Output is correct
5 Correct 0 ms 204 KB Output is correct
6 Correct 1 ms 204 KB Output is correct
7 Correct 1 ms 204 KB Output is correct
8 Correct 1 ms 204 KB Output is correct
9 Correct 0 ms 204 KB Output is correct
10 Correct 1 ms 204 KB Output is correct
11 Correct 0 ms 204 KB Output is correct
12 Correct 0 ms 204 KB Output is correct
13 Correct 1 ms 204 KB Output is correct
14 Correct 1 ms 204 KB Output is correct
15 Correct 5 ms 292 KB Output is correct