Tasks Details
easy
1.
PermCheck
Check whether array A is a permutation.
Task Score
100%
Correctness
100%
Performance
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] = 2is a permutation, but array A such that:
A[0] = 4 A[1] = 1 A[2] = 3is 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] = 2the function should return 1.
Given array A such that:
A[0] = 4 A[1] = 1 A[2] = 3the 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].
Copyright 2009–2025 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used JavaScript
Time spent on task 6 minutes
Notes
not defined yet
Code: 09:17:40 UTC,
js,
verify,
result: Passed
// you can use console.log for debugging purposes, i.e.
// console.log('this is a debug message');
function solution(A) {
var len = A.length, i, res = [];
for (i = 0; i < len; i++) {
var e = A[i];
if (e < 1 || e > len) { return 0; }
else if ( res[e - 1] === 1 ) { return 0; }
else { res[e - 1] = 1; }
}
return 1;
}
Analysis
Code: 09:17:48 UTC,
js,
verify,
result: Passed
// you can use console.log for debugging purposes, i.e.
// console.log('this is a debug message');
function solution(A) {
var len = A.length, i, res = [];
for (i = 0; i < len; i++) {
var e = A[i];
if (e < 1 || e > len) { return 0; }
else if ( res[e - 1] === 1 ) { return 0; }
else { res[e - 1] = 1; }
}
return 1;
}
Analysis
Code: 09:17:50 UTC,
js,
final,
score:
100
// you can use console.log for debugging purposes, i.e.
// console.log('this is a debug message');
function solution(A) {
var len = A.length, i, res = [];
for (i = 0; i < len; i++) {
var e = A[i];
if (e < 1 || e > len) { return 0; }
else if ( res[e - 1] === 1 ) { return 0; }
else { res[e - 1] = 1; }
}
return 1;
}Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N) or O(N * log(N))
expand all
Correctness tests
1.
0.095 s
OK
2.
0.097 s
OK
1.
0.092 s
OK
2.
0.100 s
OK
1.
0.102 s
OK
2.
0.097 s
OK
3.
0.087 s
OK
4.
0.095 s
OK
1.
0.094 s
OK
2.
0.099 s
OK
3.
0.097 s
OK
4.
0.097 s
OK
1.
0.097 s
OK
2.
0.095 s
OK
expand all
Performance tests
1.
0.118 s
OK
2.
0.117 s
OK
1.
0.180 s
OK
2.
0.204 s
OK
1.
0.228 s
OK
2.
0.202 s
OK
1.
0.193 s
OK
2.
0.146 s
OK
1.
0.075 s
OK
2.
0.118 s
OK
3.
0.075 s
OK