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Submission #237671

# Submission time Handle Problem Language Result Execution time Memory
237671 2020-06-08T08:56:26 Z RiscadoA Rack (eJOI19_rack) C++14
100 / 100
 6 ms 384 KB 
#include <bits/stdc++.h>

using namespace std;

const int64_t MOD = 1000000007;

int64_t fast_pow(int64_t x, int64_t y) {
    x %= MOD;
    if (x == 0) {
        return 0;
    }

    int64_t res = 1;
    while (y > 0) {
        if (y % 2 == 1) {
            res = (res * x) % MOD;
        }

        y >>= 1;
        x = (x * x) % MOD;
    }

    return res;
}

int64_t solve(int64_t n, int64_t k) {
    if (n == 0) {
        if (k != 0) {
            abort();
        }

        return 1;
    }

    if (k % 2 == 0) {
        return solve(n - 1, k / 2);
    } else {
        int64_t k2 = 0;
        if (k > 1) {
            k2 = k / 2;
        }
        
        return (fast_pow(2, n - 1) + solve(n - 1, k2)) % MOD;
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int64_t n, k;
    cin >> n >> k;
    cout << solve(n, k - 1) << endl;
}

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 384 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 5 ms 384 KB Output is correct
5 Correct 5 ms 384 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 384 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 5 ms 384 KB Output is correct
5 Correct 5 ms 384 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Correct 5 ms 256 KB Output is correct
8 Correct 5 ms 384 KB Output is correct
9 Correct 5 ms 384 KB Output is correct
10 Correct 4 ms 384 KB Output is correct

Subtask #3
60.0 / 60.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 384 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 5 ms 384 KB Output is correct
5 Correct 5 ms 384 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Correct 5 ms 256 KB Output is correct
8 Correct 5 ms 384 KB Output is correct
9 Correct 5 ms 384 KB Output is correct
10 Correct 4 ms 384 KB Output is correct
11 Correct 5 ms 384 KB Output is correct
12 Correct 5 ms 384 KB Output is correct
13 Correct 5 ms 384 KB Output is correct
14 Correct 5 ms 384 KB Output is correct
15 Correct 6 ms 384 KB Output is correct