Maximum Product of Two Elements

/*
 * Problem : Process an array.
 * Input   : n, then n integers.
 * Output  : The largest product.
 * Approach: Two largest or two smallest.
 * Time    : O(n)
 * Space   : O(1)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    // This method solves the task. It receives the input and returns the answer.
    static long solve(int[] a) {
        // Step 1: Track the two largest and the two smallest values in one pass.
        long max1 = Long.MIN_VALUE;
        long max2 = Long.MIN_VALUE;
        long min1 = Long.MAX_VALUE;
        long min2 = Long.MAX_VALUE;

        for (int value : a) {
            if (value > max1) {
                max2 = max1;
                max1 = value;
            } else if (value > max2) {
                max2 = value;
            }
            if (value < min1) {
                min2 = min1;
                min1 = value;
            } else if (value < min2) {
                min2 = value;
            }
        }

        // Step 2: The answer is the product of the two largest, or of the two smallest (two negatives make a positive).
        return Math.max(max1 * max2, min1 * min2);
    }

    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(solve(a));
    }
}