Tasks Details
easy
1.
Distinct
Compute number of distinct values in an array.
Task Score
100%
Correctness
100%
Performance
100%
Write a function
function solution(A);
that, given an array A consisting of N integers, returns the number of distinct values in array A.
For example, given array A consisting of six elements such that:
A[0] = 2 A[1] = 1 A[2] = 1 A[3] = 2 A[4] = 3 A[5] = 1the function should return 3, because there are 3 distinct values appearing in array A, namely 1, 2 and 3.
Write an efficient algorithm for the following assumptions:
- N is an integer within the range [0..100,000];
- each element of array A is an integer within the range [−1,000,000..1,000,000].
Copyright 2009–2025 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used JavaScript
Time spent on task 4 minutes
Notes
not defined yet
Task timeline
Code: 11:12:56 UTC,
java,
autosave
Code: 11:13:24 UTC,
js,
verify,
result: Failed
Analysis
expand all
Example tests
1.
0.076 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
Invalid result type, integer expected, 'undefined' found Perhaps you are missing a 'return'?stdout:
Set { 2, 1, 3 }
Code: 11:13:47 UTC,
js,
verify,
result: Failed
Analysis
expand all
Example tests
1.
0.072 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
Invalid result type, integer expected, 'undefined' found Perhaps you are missing a 'return'?stdout:
Set { 2, 1, 3 }
Code: 11:13:53 UTC,
js,
verify,
result: Failed
Analysis
expand all
Example tests
1.
0.072 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
Invalid result type, integer expected, 'undefined' found Perhaps you are missing a 'return'?
Code: 11:14:34 UTC,
js,
verify,
result: Failed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// console.log(new Set(A))
const uniqueValues = new Set(A);
console.log(uniqueValues.length);
return (new Set(A)).length;
}
Analysis
expand all
Example tests
1.
0.072 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
Invalid result type, integer expected, 'undefined' found Perhaps you are missing a 'return'?stdout:
undefined
Code: 11:14:56 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// console.log(new Set(A))
const uniqueValues = new Set(A);
console.log(uniqueValues.);
return (new Set(A)).length;
}
Code: 11:15:01 UTC,
js,
verify,
result: Failed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// console.log(new Set(A))
const uniqueValues = new Set(A);
console.log(uniqueValues.prototype);
return (new Set(A)).length;
}
Analysis
expand all
Example tests
1.
0.076 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
Invalid result type, integer expected, 'undefined' found Perhaps you are missing a 'return'?stdout:
undefined
Code: 11:15:30 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// console.log(new Set(A))
const uniqueValues = new Set(A);
console.log(uniqueValues.prototye);
return (new Set(A)).length;
}
Code: 11:15:33 UTC,
js,
verify,
result: Failed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// console.log(new Set(A))
const uniqueValues = new Set(A);
console.log(uniqueValues.size);
return (new Set(A)).length;
}
Analysis
expand all
Example tests
1.
0.072 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
Invalid result type, integer expected, 'undefined' found Perhaps you are missing a 'return'?stdout:
3
Code: 11:15:43 UTC,
js,
verify,
result: Passed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// console.log(new Set(A))
const uniqueValues = new Set(A);
console.log(uniqueValues.size);
return (new Set(A)).size;
}
Analysis
Code: 11:15:49 UTC,
js,
verify,
result: Passed
Analysis
Code: 11:15:57 UTC,
js,
verify,
result: Passed
Analysis
Code: 11:15:59 UTC,
js,
final,
score: 
100
Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N*log(N)) or O(N)
expand all
Correctness tests
1.
0.072 s
OK
1.
0.072 s
OK
2.
0.072 s
OK
1.
0.072 s
OK
1.
0.072 s
OK
1.
0.072 s
OK
1.
0.072 s
OK
1.
0.072 s
OK
1.
0.072 s
OK
1.
0.072 s
OK