MaxPairwiseProduct.java

import java.util.*;
import java.io.*;

public class MaxPairwiseProduct {

    static int getMaxPairwiseProduct(int[] numbers) {

        int n = numbers.length;

        int posa = Integer.MIN_VALUE, posb = Integer.MIN_VALUE;

        for (int i = 0; i < n; i++) {
            if (numbers[i] > posa) {
                posb = posa;
                posa = numbers[i];
            } else if (numbers[i] > posb)
                posb = numbers[i];
        }

        return posa * posb;
    }

    public static void main(String[] args) {

        FastScanner scanner = new FastScanner(System.in);
        int n = scanner.nextInt();
        int[] numbers = new int[n];
        for (int i = 0; i < n; i++) {
            numbers[i] = scanner.nextInt();
        }
        System.out.println(getMaxPairwiseProduct(numbers));
    }

    static class FastScanner {

        BufferedReader br;
        StringTokenizer st;

        FastScanner(InputStream stream) {

            try {
                br = new BufferedReader(new InputStreamReader(stream));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        String next() {

            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {

            return Integer.parseInt(next());
        }
    }
}