문제

A non-empty 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 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.

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 [−2,147,483,648..2,147,483,647];
array A is sorted in non-decreasing order.
Copyright 2009–2023 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.

코드

// 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");
import java.util.*;
class Solution {
    public int solution(int[] A) {
        HashSet<Integer> set = new HashSet<Integer>();
        for(int i=0; i<A.length; i++){
            if(A[i]<0){
                set.add(A[i]*-1);
            }
            else{
                set.add(A[i]);
            }
        }
        return set.size();
    }
}