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:

function 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 PHP

Time spent on task 1 minutes

Notes

not defined yet

Task timeline

Code: 05:14:15 UTC, php, verify, result: Passed

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

// you can use print for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
	$length = sizeof($A);
	$count = array();
	
	$new_arr = array();
	foreach($A as $i)
		$new_arr[$i] = 1;
		
	
	for($x = 1; $x <= $length; $x++)
		if(!isset($new_arr[$x]) || isset($count[$x]))
			return 0;
		else 
			$count[$x] = 1;
	return 1;
}
solution(array(5,3,5,2,1));
solution(array(5,3,4,2,1));

Analysis

▶

example1
the first example test

✔

▶

example2
the second example test

✔

Code: 05:14:24 UTC, php, verify, result: Passed

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

// you can use print for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
	$length = sizeof($A);
	$count = array();
	
	$new_arr = array();
	foreach($A as $i)
		$new_arr[$i] = 1;
		
	
	for($x = 1; $x <= $length; $x++)
		if(!isset($new_arr[$x]) || isset($count[$x]))
			return 0;
		else 
			$count[$x] = 1;
	return 1;
}
solution(array(5,3,5,2,1));
solution(array(5,3,4,2,1));

Analysis

▶

example1
the first example test

✔

▶

example2
the second example test

✔

Code: 05:14:27 UTC, php, final, score: 100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

// you can use print for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
	$length = sizeof($A);
	$count = array();
	
	$new_arr = array();
	foreach($A as $i)
		$new_arr[$i] = 1;
		
	
	for($x = 1; $x <= $length; $x++)
		if(!isset($new_arr[$x]) || isset($count[$x]))
			return 0;
		else 
			$count[$x] = 1;
	return 1;
}
solution(array(5,3,5,2,1));
solution(array(5,3,4,2,1));

Analysis summary

The solution obtained perfect score.

Analysis

▶

example1
the first example test

✔

▶

example2
the second example test

✔

▶

extreme_min_max
single element with minimal/maximal value

✔

▶

single
single element

✔

▶

double
two elements

✔

▶

antiSum1
total sum is correct, but it is not a permutation, N = 3

✔

▶

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

✔