Tasks Details
easy
1.
Distinct
Compute number of distinct values in an array.
Task Score
100%
Correctness
100%
Performance
100%
Write a function
class Solution { public int solution(int[] 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 Java 8
Time spent on task 7 minutes
Notes
not defined yet
Task timeline
Code: 21:07:06 UTC,
java,
verify,
result: Failed
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] distinct = IntStream.of(A).distinct.toArray();
return distinct.length;
}
}
Analysis
Compile error
Solution.java:10: error: cannot find symbol
int[] distinct = IntStream.of(A).distinct.toArray();
^
symbol: variable IntStream
location: class Solution
1 error
Code: 21:07:26 UTC,
java,
verify,
result: Failed
// you can also use imports, for example:
import java.util.stream.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] distinct = IntStream.of(A).distinct.toArray();
return distinct.length;
}
}
Analysis
Compile error
Solution.java:10: error: cannot find symbol
int[] distinct = IntStream.of(A).distinct.toArray();
^
symbol: variable distinct
location: interface IntStream
1 error
Code: 21:09:00 UTC,
java,
verify,
result: Passed
// you can also use imports, for example:
import java.util.stream.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] distinct = IntStream.of(A).distinct().toArray();
return distinct.length;
}
}
Analysis
Code: 21:09:18 UTC,
java,
verify,
result: Passed
Analysis
Code: 21:09:32 UTC,
java,
verify,
result: Passed
Analysis
Code: 21:10:48 UTC,
java,
verify,
result: Passed
Analysis
Code: 21:10:56 UTC,
java,
final,
score:
100
Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N) or O(N*log(N))
expand all
Correctness tests
1.
1.891 s
OK
1.
1.867 s
OK
2.
1.968 s
OK
1.
1.962 s
OK
1.
1.977 s
OK
1.
1.966 s
OK
1.
1.975 s
OK
1.
1.996 s
OK
1.
1.976 s
OK
1.
1.976 s
OK