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 2009–2024 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used Java 8
Time spent on task 2 minutes
Notes
not defined yet
Task timeline
Code: 16:01:47 UTC,
c,
verify,
result: Failed
Analysis
Compile error
func.c:4:9: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'static'
Code: 16:01:55 UTC,
c,
verify,
result: Failed
Analysis
Compile error
func.c:1:1: error: unknown type name 'import' func.c:1:12: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token func.c:3:9: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'static'
Code: 16:02:11 UTC,
c,
verify,
result: Failed
Analysis
Compile error
func.c:1:1: error: unknown type name 'import' func.c:1:12: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token func.c:2:2: error: unknown type name 'import' func.c:2:13: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token func.c:4:9: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'static'
Code: 16:02:21 UTC,
c,
verify,
result: Failed
Analysis
Compile error
func.c:1:1: error: unknown type name 'import' func.c:1:12: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token func.c:2:1: error: unknown type name 'import' func.c:2:12: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token func.c:4:9: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'static'
Code: 16:02:43 UTC,
java,
verify,
result: Failed
Analysis
Compile error
Solution.java:4: error: class, interface, or enum expected
public static int solution(int[] A) {
^
Solution.java:6: error: class, interface, or enum expected
return (int) (((N*(N+1))/2)-IntStream.of(A).sum());
^
Solution.java:7: error: class, interface, or enum expected
}
^
3 errors
Code: 16:03:01 UTC,
java,
verify,
result: Failed
Analysis
Compile error
Solution.java:4: error: class, interface, or enum expected
public int solution(int[] A) {
^
Solution.java:6: error: class, interface, or enum expected
return (int) (((N*(N+1))/2)-IntStream.of(A).sum());
^
Solution.java:7: error: class, interface, or enum expected
}
^
3 errors
Code: 16:03:27 UTC,
java,
verify,
result: Passed
import java.text.ParseException;
import java.util.stream.IntStream;
// you can also use imports, for example:
// import java.util.*;
// you can use System.out.println for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
long N = A.length + 1;
return (int) (((N*(N+1))/2)-IntStream.of(A).sum());
}
}
Analysis
Code: 16:03:35 UTC,
java,
verify,
result: Passed
import java.text.ParseException;
import java.util.stream.IntStream;
// you can also use imports, for example:
// import java.util.*;
// you can use System.out.println for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
long N = A.length + 1;
return (int) (((N*(N+1))/2)-IntStream.of(A).sum());
}
}
Analysis
Code: 16:03:42 UTC,
java,
final,
score:
100
import java.text.ParseException;
import java.util.stream.IntStream;
// you can also use imports, for example:
// import java.util.*;
// you can use System.out.println for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
long N = A.length + 1;
return (int) (((N*(N+1))/2)-IntStream.of(A).sum());
}
}
Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N * log(N)) or O(N)