gistfile1.java

package algo.task;

public class Task4 {

	public static void main(String[] args) {
		int[] test = {1, 2, 3, 1, 5, 2, 4};
		findDuplicates(test);
	}

	public static void findDuplicates(int array[]) {
		for (int i = 0; i < array.length; i++) {
			if (array[Math.abs(array[i])] >= 0) {
				array[Math.abs(array[i])] *= -1;				
			} else {
				System.out.println("Duplicate: " + Math.abs(array[i]));
			}
		}
	}
}