Test results - Codility

Tasks Details

easy

1. PermCheck

Check whether array A is a permutation.

70%

40%

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:

def solution(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 Python

Time spent on task 1 minutes

Notes

not defined yet

Task timeline

Code: 10:40:59 UTC, py, verify, result: Passed

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

# you can write to stdout for debugging purposes, e.g.
# print "this is a debug message"

def solution(A):

    if len(A) == 0:
        return 0
   
    A.sort()
    
    for i in range(1, len(A)):
        if (A[i-1] != (A[i] - 1)):
            return 0
    return 1
    pass

Analysis

▶

example1
the first example test

✔

▶

example2
the second example test

✔

Code: 10:41:03 UTC, py, verify, result: Passed

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

# you can write to stdout for debugging purposes, e.g.
# print "this is a debug message"

def solution(A):

    if len(A) == 0:
        return 0
   
    A.sort()
    
    for i in range(1, len(A)):
        if (A[i-1] != (A[i] - 1)):
            return 0
    return 1
    pass

Analysis

▶

example1
the first example test

✔

▶

example2
the second example test

✔

Code: 10:41:06 UTC, py, final, score: 70

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

# you can write to stdout for debugging purposes, e.g.
# print "this is a debug message"

def solution(A):

    if len(A) == 0:
        return 0
   
    A.sort()
    
    for i in range(1, len(A)):
        if (A[i-1] != (A[i] - 1)):
            return 0
    return 1
    pass

Analysis summary

The following issues have been detected: wrong answers.

For example, for the input [2] the solution returned a wrong answer (got 1 expected 0).

Analysis

▶

example1
the first example test

✔

▶

example2
the second example test

✔

▶

extreme_min_max
single element with minimal/maximal value

✘

WRONG ANSWER
got 1 expected 0

▶

single
single element

✘

WRONG ANSWER
got 1 expected 0

▶

double
two elements

✘

WRONG ANSWER
got 1 expected 0

▶

antiSum1
total sum is correct, but it is not a permutation, N <= 10

✔

▶

small_permutation
permutation + one element occurs twice, N = ~100

✔

▶

medium_permutation
permutation + few elements occur twice, N = ~10,000

✔

▶

antiSum2
total sum is correct, but it is not a permutation, N = ~100,000

✔

▶

large_permutation
permutation + one element occurs three times, N = ~100,000

✔

▶

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

✔

▶

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

✔