[Codility] Sorting - Distinct / Java

1. 문제

Write a function

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

that, given an array A consisting of N integers, returns the number of distinct values in array A.

For example, given array A consisting of six elements such that:

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

the function should return 3, because there are 3 distinct values appearing in array A, namely 1, 2 and 3.

Write an efficient algorithm for the following assumptions:

• N is an integer within the range [0..100,000];
• each element of array A is an integer within the range [−1,000,000..1,000,000].

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2. 코드

import java.util.*;

class Solution {
    public int solution(int[] A) {
        HashSet<Integer> set = new HashSet<>();
        
        for(int i=0; i<A.length; i++) {
            set.add(A[i]);
        }
        
        return set.size();
    }
}