Test results - Codility

Tasks Details

medium

1. CountNonDivisible

Calculate the number of elements of an array that are not divisors of each element.

Task Score

100%

Correctness

100%

Performance

100%

You are given an array A consisting of N integers.

For each number A[i] such that 0 ≤ i < N, we want to count the number of elements of the array that are not the divisors of A[i]. We say that these elements are non-divisors.

For example, consider integer N = 5 and array A such that:

A[0] = 3 A[1] = 1 A[2] = 2 A[3] = 3 A[4] = 6

For the following elements:

A[0] = 3, the non-divisors are: 2, 6,

A[1] = 1, the non-divisors are: 3, 2, 3, 6,

A[2] = 2, the non-divisors are: 3, 3, 6,

A[3] = 3, the non-divisors are: 2, 6,

A[4] = 6, there aren't any non-divisors.

Write a function:

vector<int> solution(vector<int> &A);

that, given an array A consisting of N integers, returns a sequence of integers representing the amount of non-divisors.

Result array should be returned as a vector of integers.

For example, given:

A[0] = 3 A[1] = 1 A[2] = 2 A[3] = 3 A[4] = 6

the function should return [2, 4, 3, 2, 0], as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [1..50,000];

each element of array A is an integer within the range [1..2 * N].

Solution

Programming language used C++

Time spent on task 3 minutes

Notes

not defined yet

Code: 19:58:48 UTC, java, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11

// you can also use imports, for example:
// import java.util.*;

// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");

class Solution {
    public int[] solution(int[] A) {
        // write your code in Java SE 8
    }
}

Code: 20:00:14 UTC, cpp, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9

// you can use includes, for example:
// #include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

vector<int> solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
}

Code: 20:00:24 UTC, cpp, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

// you can use includes, for example:
// #include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

vector<int> solution(vector<int> &A) {
    const int N = A.size();

    std::unordered_map<int, int> frequencies;

    for (auto v : A) {
        if (frequencies.find(v) == frequencies.end()) {
            frequencies[v] = 1;
        } else {
            frequencies[v]++;
        }
    }

    std::unordered_map<int, std::vector<int>> divisorsMap;

    for (auto v : A) {
        if (divisorsMap.find(v) == divisorsMap.end()) {
            std::vector<int> divisors = list_divisors(v);
            divisorsMap[v] = divisors;
        }
    }

    std::vector<int> result(N);

    for (int i = 0; i < N; ++i) {
        int non_divisors = N;
        int v = A[i];
        std::vector<int> &divisors = divisorsMap[v];

        for (int d : divisors) {
            if (frequencies.find(d) != frequencies.end()) {
                non_divisors -= frequencies[d];
            }
        }
        result[i] = non_divisors;
    }

    return result;
}

Code: 20:00:35 UTC, cpp, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67

// you can use includes, for example:
// #include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;


std::vector<int> list_divisors(int n) {
    std::vector<int> result;

    result.push_back(1);
    if (n > 1) {
        int k = 2;
        while(k * k <= n) {
            if (n % k == 0) {
                result.push_back(k);
                int b = n / k;
                if (b != k) {
                   result.push_back(b);
                }
            }
            k ++;
        }
        result.push_back(n);
    }
    return result;
}

vector<int> solution(vector<int> &A) {
    const int N = A.size();

    std::unordered_map<int, int> frequencies;

    for (auto v : A) {
        if (frequencies.find(v) == frequencies.end()) {
            frequencies[v] = 1;
        } else {
            frequencies[v]++;
        }
    }

    std::unordered_map<int, std::vector<int>> divisorsMap;

    for (auto v : A) {
        if (divisorsMap.find(v) == divisorsMap.end()) {
            std::vector<int> divisors = list_divisors(v);
            divisorsMap[v] = divisors;
        }
    }

    std::vector<int> result(N);

    for (int i = 0; i < N; ++i) {
        int non_divisors = N;
        int v = A[i];
        std::vector<int> &divisors = divisorsMap[v];

        for (int d : divisors) {
            if (frequencies.find(d) != frequencies.end()) {
                non_divisors -= frequencies[d];
            }
        }
        result[i] = non_divisors;
    }

    return result;
}

Code: 20:00:42 UTC, cpp, verify, result: Passed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68

// you can use includes, for example:
// 
#include <unordered_map>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;


std::vector<int> list_divisors(int n) {
    std::vector<int> result;

    result.push_back(1);
    if (n > 1) {
        int k = 2;
        while(k * k <= n) {
            if (n % k == 0) {
                result.push_back(k);
                int b = n / k;
                if (b != k) {
                   result.push_back(b);
                }
            }
            k ++;
        }
        result.push_back(n);
    }
    return result;
}

vector<int> solution(vector<int> &A) {
    const int N = A.size();

    std::unordered_map<int, int> frequencies;

    for (auto v : A) {
        if (frequencies.find(v) == frequencies.end()) {
            frequencies[v] = 1;
        } else {
            frequencies[v]++;
        }
    }

    std::unordered_map<int, std::vector<int>> divisorsMap;

    for (auto v : A) {
        if (divisorsMap.find(v) == divisorsMap.end()) {
            std::vector<int> divisors = list_divisors(v);
            divisorsMap[v] = divisors;
        }
    }

    std::vector<int> result(N);

    for (int i = 0; i < N; ++i) {
        int non_divisors = N;
        int v = A[i];
        std::vector<int> &divisors = divisorsMap[v];

        for (int d : divisors) {
            if (frequencies.find(d) != frequencies.end()) {
                non_divisors -= frequencies[d];
            }
        }
        result[i] = non_divisors;
    }

    return result;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.001 s

Code: 20:00:52 UTC, cpp, verify, result: Passed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68

// you can use includes, for example:
// 
#include <unordered_map>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;


std::vector<int> list_divisors(int n) {
    std::vector<int> result;

    result.push_back(1);
    if (n > 1) {
        int k = 2;
        while(k * k <= n) {
            if (n % k == 0) {
                result.push_back(k);
                int b = n / k;
                if (b != k) {
                   result.push_back(b);
                }
            }
            k ++;
        }
        result.push_back(n);
    }
    return result;
}

vector<int> solution(vector<int> &A) {
    const int N = A.size();

    std::unordered_map<int, int> frequencies;

    for (auto v : A) {
        if (frequencies.find(v) == frequencies.end()) {
            frequencies[v] = 1;
        } else {
            frequencies[v]++;
        }
    }

    std::unordered_map<int, std::vector<int>> divisorsMap;

    for (auto v : A) {
        if (divisorsMap.find(v) == divisorsMap.end()) {
            std::vector<int> divisors = list_divisors(v);
            divisorsMap[v] = divisors;
        }
    }

    std::vector<int> result(N);

    for (int i = 0; i < N; ++i) {
        int non_divisors = N;
        int v = A[i];
        std::vector<int> &divisors = divisorsMap[v];

        for (int d : divisors) {
            if (frequencies.find(d) != frequencies.end()) {
                non_divisors -= frequencies[d];
            }
        }
        result[i] = non_divisors;
    }

    return result;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.001 s

Code: 20:00:56 UTC, cpp, final, score: 100

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68

// you can use includes, for example:
// 
#include <unordered_map>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;


std::vector<int> list_divisors(int n) {
    std::vector<int> result;

    result.push_back(1);
    if (n > 1) {
        int k = 2;
        while(k * k <= n) {
            if (n % k == 0) {
                result.push_back(k);
                int b = n / k;
                if (b != k) {
                   result.push_back(b);
                }
            }
            k ++;
        }
        result.push_back(n);
    }
    return result;
}

vector<int> solution(vector<int> &A) {
    const int N = A.size();

    std::unordered_map<int, int> frequencies;

    for (auto v : A) {
        if (frequencies.find(v) == frequencies.end()) {
            frequencies[v] = 1;
        } else {
            frequencies[v]++;
        }
    }

    std::unordered_map<int, std::vector<int>> divisorsMap;

    for (auto v : A) {
        if (divisorsMap.find(v) == divisorsMap.end()) {
            std::vector<int> divisors = list_divisors(v);
            divisorsMap[v] = divisors;
        }
    }

    std::vector<int> result(N);

    for (int i = 0; i < N; ++i) {
        int non_divisors = N;
        int v = A[i];
        std::vector<int> &divisors = divisorsMap[v];

        for (int d : divisors) {
            if (frequencies.find(d) != frequencies.end()) {
                non_divisors -= frequencies[d];
            }
        }
        result[i] = non_divisors;
    }

    return result;
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N * log(N))

expand all Example tests

▶

example
example test

✔

0.001 s

expand all Correctness tests

▶

extreme_simple
extreme simple

✔

0.001 s

▶

double
two elements

✔

0.001 s

▶

simple
simple tests

✔

0.001 s

▶

primes
prime numbers

✔

0.001 s

▶

small_random
small, random numbers, length = 100

✔

0.001 s

expand all Performance tests

▶

medium_random
medium, random numbers length = 5,000

✔

0.008 s

0.004 s

▶

large_range
1, 2, ..., N, length = ~20,000

✔

0.032 s

0.008 s

▶

large_random
large, random numbers, length = ~30,000

✔

0.052 s

0.016 s

▶

large_extreme
large, all the same values, length = 50,000

✔

0.036 s

0.008 s

0.012 s