Tasks Details
easy
1.
PermCheck
Check whether array A is a permutation.
Task Score
100%
Correctness
100%
Performance
100%
A non-empty array A consisting of N integers is given.
A permutation is a sequence containing each element from 1 to N once, and only once.
For example, array A such that:
A[0] = 4 A[1] = 1 A[2] = 3 A[3] = 2is a permutation, but array A such that:
A[0] = 4 A[1] = 1 A[2] = 3is not a permutation, because value 2 is missing.
The goal is to check whether array A is a permutation.
Write a function:
class Solution { public int solution(int[] A); }
that, given an array A, returns 1 if array A is a permutation and 0 if it is not.
For example, given array A such that:
A[0] = 4 A[1] = 1 A[2] = 3 A[3] = 2the function should return 1.
Given array A such that:
A[0] = 4 A[1] = 1 A[2] = 3the function should return 0.
Write an efficient algorithm for the following assumptions:
- N is an integer within the range [1..100,000];
- each element of array A is an integer within the range [1..1,000,000,000].
Copyright 2009–2025 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used Java 21
Time spent on task 6 minutes
Notes
not defined yet
Code: 21:40:52 UTC,
java,
verify,
result: Passed
// 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) {
// write your code in Java SE 8
int[] B = new int[A.length];
for (int i=0; i<A.length; i++){
if (A[i]>A.length) return 0;
int pos = A[i]-1;
if (B[pos]>0) return 0;
B[pos] = A[i];
}
return 1;
}
}
Analysis
Code: 21:41:22 UTC,
java,
verify,
result: Passed
// 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) {
// write your code in Java SE 8
int[] B = new int[A.length];
for (int i=0; i<A.length; i++){
if (A[i]>A.length) return 0;
int pos = A[i]-1;
if (B[pos]>0) return 0;
B[pos] = A[i];
}
return 1;
}
}
Analysis
Code: 21:41:30 UTC,
java,
final,
score:
100
// 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) {
// write your code in Java SE 8
int[] B = new int[A.length];
for (int i=0; i<A.length; i++){
if (A[i]>A.length) return 0;
int pos = A[i]-1;
if (B[pos]>0) return 0;
B[pos] = A[i];
}
return 1;
}
}
Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N) or O(N * log(N))
expand all
Correctness tests
1.
1.312 s
OK
2.
1.326 s
OK
1.
1.320 s
OK
2.
1.313 s
OK
1.
1.316 s
OK
2.
1.315 s
OK
3.
1.313 s
OK
4.
1.315 s
OK
1.
1.320 s
OK
2.
1.314 s
OK
3.
1.316 s
OK
4.
1.315 s
OK
1.
1.306 s
OK
2.
1.334 s
OK
expand all
Performance tests
1.
1.339 s
OK
2.
1.305 s
OK
1.
1.576 s
OK
2.
1.571 s
OK
1.
1.559 s
OK
2.
1.579 s
OK
1.
1.583 s
OK
2.
1.575 s
OK
1.
1.254 s
OK
2.
1.451 s
OK
3.
1.315 s
OK