Remove Duplicates from a Sorted Array

/*
 * Problem : Process an array.
 * Input   : n, then n integers.
 * Output  : The array without duplicates.
 * Approach: Two pointers.
 * Time    : O(n)
 * Space   : O(1)
 * Java    : 8 or newer.
 */
import java.util.Scanner;
import java.util.Arrays;
import java.util.stream.Collectors;

public class Main {
    // This method solves the task. It receives the input and returns the answer.
    static int[] solve(int[] a) {
        // Step 1: unique is the number of different values found so far. The first element is always kept.
        int unique = 1;

        // Step 2: Compare every element with the last kept value.
        for (int i = 1; i < a.length; i++) {
            // Step 3: A new value goes to the next free place.
            if (a[i] != a[unique - 1]) {
                a[unique] = a[i];
                unique++;
            }
        }

        // Step 4: Return only the first "unique" elements.
        return java.util.Arrays.copyOf(a, unique);
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int size = scanner.nextInt();
        int[] a = new int[size];
        for (int i = 0; i < size; i++) {
            a[i] = scanner.nextInt();
        }
        System.out.println(Arrays.stream(solve(a)).mapToObj(String::valueOf).collect(Collectors.joining(" ")));
    }
}