Tasks Details
easy
Find the missing element in a given permutation.
Task Score
100%
Correctness
100%
Performance
100%
An array A consisting of N different integers is given. The array contains integers in the range [1..(N + 1)], which means that exactly one element is missing.
Your goal is to find that missing element.
Write a function:
class Solution { public int solution(int[] A); }
that, given an array A, returns the value of the missing element.
For example, given array A such that:
A[0] = 2 A[1] = 3 A[2] = 1 A[3] = 5the function should return 4, as it is the missing element.
Write an efficient algorithm for the following assumptions:
- N is an integer within the range [0..100,000];
- the elements of A are all distinct;
- each element of array A is an integer within the range [1..(N + 1)].
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 5 minutes
Notes
not defined yet
Code: 11:30:35 UTC,
java,
autosave
Code: 11:30:42 UTC,
java,
autosave
Code: 11:32:23 UTC,
java,
verify,
result: Passed
import java.util.*;
class Solution {
public int solution(int[] A) {
boolean[] array = new boolean[100001];
for (int a : A) {
array[a] = true;
}
for (int i = 1; i <= array.length; i++) {
if (!array[i]) {
return i;
}
}
return 100001;
}
}
User test case 1:
[0, 100000]
Analysis
Code: 11:33:34 UTC,
java,
verify,
result: Passed
import java.util.*;
class Solution {
public int solution(int[] A) {
boolean[] array = new boolean[100001];
for (int a : A) {
array[a] = true;
}
for (int i = 1; i <= array.length; i++) {
if (!array[i]) {
return i;
}
}
return 100001;
}
}
User test case 1:
[0, 100000]
Analysis
Code: 11:34:54 UTC,
java,
verify,
result: Passed
import java.util.*;
class Solution {
public int solution(int[] A) {
boolean[] array = new boolean[100001];
for (int a : A) {
array[a] = true;
}
for (int i = 1; i <= array.length; i++) {
if (!array[i]) {
return i;
}
}
return 100001;
}
}
User test case 1:
[0, 100001]
Analysis
expand all
User tests
1.
0.008 s
RUNTIME ERROR,
tested program terminated unexpectedly
stderr:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 100001 at Solution.solution(Solution.java:7) at Exec.run(exec.java:46) at Exec.main(exec.java:31)
Code: 11:34:57 UTC,
java,
autosave
Code: 11:35:00 UTC,
java,
verify,
result: Passed
import java.util.*;
class Solution {
public int solution(int[] A) {
boolean[] array = new boolean[100002];
for (int a : A) {
array[a] = true;
}
for (int i = 1; i <= array.length; i++) {
if (!array[i]) {
return i;
}
}
return 100001;
}
}
User test case 1:
[0, 100001]
Analysis
Code: 11:35:05 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.
0.004 s
OK
2.
0.004 s
OK
1.
0.004 s
OK
2.
0.004 s
OK
1.
0.004 s
OK
2.
0.004 s
OK
1.
0.004 s
OK
2.
0.004 s
OK
3.
0.004 s
OK
1.
0.004 s
OK
expand all
Performance tests
1.
0.024 s
OK
1.
0.028 s
OK
1.
0.264 s
OK
2.
0.120 s
OK
3.
0.120 s
OK
1.
0.240 s
OK
1.
0.144 s
OK