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 6 minutes
Notes
not defined yet
Code: 09:04:43 UTC,
java,
autosave
Code: 09:05:49 UTC,
java,
autosave
Code: 09:06:19 UTC,
java,
autosave
Code: 09:06:32 UTC,
java,
autosave
// 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) {
Set<Integer> distinctValues = new HashSet<>();
for(int value: A.)
}
}
Code: 09:07:02 UTC,
java,
autosave
// 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) {
Set<Integer> distinctValues = new HashSet<>();
for(int value: A.values) {
disctinctValues.add(value);
}
return disctinctValues.size();
}
}
Code: 09:07:07 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) {
Set<Integer> distinctValues = new HashSet<>();
for(int value: A.values) {
disctinctValues.add(value);
}
return disctinctValues.size();
}
}
Analysis
Compile error
Solution.java:10: error: cannot find symbol
for(int value: A.values) {
^
symbol: variable values
location: variable A of type int[]
Solution.java:11: error: cannot find symbol
disctinctValues.add(value);
^
symbol: variable disctinctValues
location: class Solution
Solution.java:13: error: cannot find symbol
return disctinctValues.size();
^
symbol: variable disctinctValues
location: class Solution
3 errors
Code: 09:07:29 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) {
Set<Integer> distinctValues = new HashSet<>();
for(int value: A.values) {
disctinctValues.add(value);
}
return disctinctValues.length();
}
}
Analysis
Compile error
Solution.java:10: error: cannot find symbol
for(int value: A.values) {
^
symbol: variable values
location: variable A of type int[]
Solution.java:11: error: cannot find symbol
disctinctValues.add(value);
^
symbol: variable disctinctValues
location: class Solution
Solution.java:13: error: cannot find symbol
return disctinctValues.length();
^
symbol: variable disctinctValues
location: class Solution
3 errors
Code: 09:07:43 UTC,
java,
autosave
// 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) {
Set<Integer> distinctValues = new HashSet<>();
for(int value: A.values) {
disctinctValues.add(value);
}
return distinctValues.length();
}
}
Code: 09:07:46 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) {
Set<Integer> distinctValues = new HashSet<>();
for(int value: A.values) {
disctinctValues.add(value);
}
return distinctValues.size();
}
}
Analysis
Compile error
Solution.java:10: error: cannot find symbol
for(int value: A.values) {
^
symbol: variable values
location: variable A of type int[]
Solution.java:11: error: cannot find symbol
disctinctValues.add(value);
^
symbol: variable disctinctValues
location: class Solution
2 errors
Code: 09:08:06 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) {
Set<Integer> distinctValues = new HashSet<>();
for(int value: A.values) {
distinctValues.add(value);
}
return distinctValues.size();
}
}
Analysis
Compile error
Solution.java:10: error: cannot find symbol
for(int value: A.values) {
^
symbol: variable values
location: variable A of type int[]
1 error
Code: 09:08:16 UTC,
java,
autosave
// 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) {
Set<Integer> distinctValues = new HashSet<>();
for(int value: A.values()) {
distinctValues.add(value);
}
return distinctValues.size();
}
}
Code: 09:08:17 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) {
Set<Integer> distinctValues = new HashSet<>();
for(int value: A.values()) {
distinctValues.add(value);
}
return distinctValues.size();
}
}
Analysis
Compile error
Solution.java:10: error: cannot find symbol
for(int value: A.values()) {
^
symbol: method values()
location: variable A of type int[]
1 error
Code: 09:09:03 UTC,
java,
autosave
// 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) {
Set<Integer> distinctValues = new HashSet<>();
for(int value: A.values() {
distinctValues.add(value);
}
return distinctValues.size();
}
}
Code: 09:09:12 UTC,
java,
verify,
result: Passed
// 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) {
Set<Integer> distinctValues = new HashSet<>();
for (int value: A) {
distinctValues.add(value);
}
return distinctValues.size();
}
}
Analysis
Code: 09:09:45 UTC,
java,
verify,
result: Passed
// 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) {
Set<Integer> distinctValues = new HashSet<>();
for (int value: A) {
distinctValues.add(value);
}
return distinctValues.size();
}
}
Analysis
Code: 09:09:49 UTC,
java,
final,
score:
100
// 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) {
Set<Integer> distinctValues = new HashSet<>();
for (int value: A) {
distinctValues.add(value);
}
return distinctValues.size();
}
}Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N*log(N)) or O(N)
expand all
Correctness tests
1.
0.008 s
OK
1.
0.004 s
OK
2.
0.008 s
OK
1.
0.004 s
OK
1.
0.004 s
OK
1.
0.004 s
OK
1.
0.004 s
OK
1.
0.008 s
OK
1.
0.004 s
OK
1.
0.004 s
OK