https://codejam.withgoogle.com/2018/challenges/00000000000000cb/dashboard/00000000000079cb

TroubleSort.java

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

class TroubleSort {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        int T = scanner.nextInt();

        FOR:
        for (int t = 0; t < T; t++) {
            int N = scanner.nextInt();
            int[] V = new int[N];
            List<Integer> evens = new ArrayList<>();
            List<Integer> odds = new ArrayList<>();
            for (int n = 0; n < N; n++) {
                if (n % 2 == 0) {
                    evens.add(scanner.nextInt());
                } else {
                    odds.add(scanner.nextInt());
                }
            }
            Collections.sort(evens);
            Collections.sort(odds);
            for (int n = 0; n < N; n++) {
                if (n % 2 == 0) {
                    V[n] = evens.get(n / 2);
                } else {
                    V[n] = odds.get(n / 2);
                }
            }

            for (int i = 0; i < V.length - 1; i++) {
                if (V[i] > V[i + 1]) {
                    System.out.println("Case #" + (t + 1) + ": " + i);
                    continue FOR;
                }
            }
            System.out.println("Case #" + (t + 1) + ": OK");
        }
    }
}