Codility - Lesson 15 Caterpillar Method - 1. AbsDistinct

Source Link:

https://app.codility.com/programmers/lessons/15-caterpillar_method/abs_distinct/

Question:

A non-empty zero-indexed array A consisting of N numbers is given. The array is sorted in non-decreasing order. The absolute distinct count of this array is the number of distinct absolute values among the elements of the array.

For example, consider array A such that:

A[0] = -5 A[1] = -3 A[2] = -1 A[3] = 0 A[4] = 3 A[5] = 6

The absolute distinct count of this array is 5, because there are 5 distinct absolute values among the elements of this array, namely 0, 1, 3, 5 and 6.

Write a function:

class Solution { public int solution(int[] A); }

that, given a non-empty zero-indexed array A consisting of N numbers, returns absolute distinct count of array A.

For example, given array A such that:

A[0] = -5 A[1] = -3 A[2] = -1 A[3] = 0 A[4] = 3 A[5] = 6

the function should return 5, as explained above.

Assume that:

• N is an integer within the range [1..100,000];
• each element of array A is an integer within the range [−2,147,483,648..2,147,483,647];
• array A is sorted in non-decreasing order.

Complexity:

• expected worst-case time complexity is O(N);
• expected worst-case space complexity is O(N), beyond input storage (not counting the storage required for input arguments).

My Solution:

Notes:

1. // using "Set"
Set<Integer> set = new HashSet<>();

2. // note: using "Math.abs(int)"
if( set.contains( Math.abs(A[i]) ) == false ){
set.add( Math.abs(A[i]) );
}

3. 
return set.size();