Test results - Codility

Tasks Details

easy

1. PermCheck

Check whether array A is a permutation.

100%

A non-empty array A consisting of N integers is given.

A permutation is a sequence containing each element from 1 to N once, and only once.

For example, array A such that:

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

is a permutation, but array A such that:

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

is not a permutation, because value 2 is missing.

The goal is to check whether array A is a permutation.

Write a function:

class Solution { public int solution(int[] A); }

that, given an array A, returns 1 if array A is a permutation and 0 if it is not.

For example, given array A such that:

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

the function should return 1.

Given array A such that:

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

the function should return 0.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [1..100,000];

each element of array A is an integer within the range [1..1,000,000,000].

Solution

Programming language used Java 8

Time spent on task 13 minutes

Notes

not defined yet

Task timeline

Code: 23:51:57 UTC, java, verify, result: Failed

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

// you can also use imports, for example:
// import java.math.*;
class Solution {
    public int solution(int[] A) {
        int[] counts = new int[A.length];

        for(int i = 0; i < A.length; i++)
        {
            if(A[i] > A.length)
            {
                return 0;
            }
            else if(counts[A[i]] > 0)
            {
                return 0;
            }
            else
            {
                counts[A[i]] = 1;
            }
        }

        return 0;
    }
}

Analysis

▶

example1
the first example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

▶

example2
the second example test

✔

Code: 23:52:39 UTC, java, verify, result: Failed

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

// you can also use imports, for example:
// import java.math.*;
class Solution {
    public int solution(int[] A) {
        int[] counts = new int[A.length];

        for(int i = 0; i < A.length; i++)
        {
            if(A[i] > A.length)
            {
                return 0;
            }
            else if(counts[A[i] - 1] > 0)
            {
                return 0;
            }
            else
            {
                counts[A[i] - 1] = 1;
            }
        }

        return 0;
    }
}

Analysis

▶

example1
the first example test

✘

WRONG ANSWER
got 0 expected 1

▶

example2
the second example test

✔

Code: 23:54:11 UTC, java, verify, result: Passed

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

// you can also use imports, for example:
// import java.math.*;
class Solution {
    public int solution(int[] A) {
        int[] counts = new int[A.length];

        for(int i = 0; i < A.length; i++)
        {
            if(A[i] > A.length)
            {
                return 0;
            }
            else if(counts[A[i] - 1] > 0)
            {
                return 0;
            }
            else
            {
                counts[A[i] - 1] = 1;
            }
        }

        return 1;
    }
}

Analysis

▶

example1
the first example test

✔

▶

example2
the second example test

✔

▶

test_data0

✔

Code: 23:54:28 UTC, java, verify, result: Passed

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

// you can also use imports, for example:
// import java.math.*;
class Solution {
    public int solution(int[] A) {
        int[] counts = new int[A.length];

        for(int i = 0; i < A.length; i++)
        {
            if(A[i] > A.length)
            {
                return 0;
            }
            else if(counts[A[i] - 1] > 0)
            {
                return 0;
            }
            else
            {
                counts[A[i] - 1] = 1;
            }
        }

        return 1;
    }
}

Analysis

▶

example1
the first example test

✔

▶

example2
the second example test

✔

▶

test_data0

✔

Code: 23:54:36 UTC, java, final, score: 100

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

// you can also use imports, for example:
// import java.math.*;
class Solution {
    public int solution(int[] A) {
        int[] counts = new int[A.length];

        for(int i = 0; i < A.length; i++)
        {
            if(A[i] > A.length)
            {
                return 0;
            }
            else if(counts[A[i] - 1] > 0)
            {
                return 0;
            }
            else
            {
                counts[A[i] - 1] = 1;
            }
        }

        return 1;
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N) or O(N * log(N))

▶

example1
the first example test

✔

▶

example2
the second example test

✔

▶

extreme_max
single element with maximal value

✔

▶

single
single element

✔

▶

double
two elements

✔

▶

antiSum1
total sum is corret (equals 1 + 2 + ... N), but it is not a permutation, N = 3

✔

▶

medium_permutation
permutation, N = ~10,000

✔

▶

antiSum2
total sum is corret (equals 1 + 2 + ... N), but it is not a permutation, N = ~100,000

✔

▶

large_permutation
large permutation, N = ~100,000

✔

▶

large_range
sequence 1, 2, ..., N, N = ~100,000

✔

▶

extreme_values
all the same values, N = ~100,000

✔