Problem448.java

import java.util.*;

class Problem448 {
	public static void main(String[] args) {
		int[] nums = {4,3,2,7,8,2,3,1};
		System.out.println(new Problem448().findDisappearedNumbers(nums));
	}

	public List<Integer> findDisappearedNumbers(int[] nums) {
 for (int i = 0; i < nums.length; i++) {
 	int k = nums[i];
	 int tmp = 0;
	 	while (nums[k-1] != k) {
	 		tmp = nums[k-1];
	 		nums[k-1] = k;
	 		k = tmp;
	 	}
 }
 
 List<Integer> list = new ArrayList<>();

 for (int i = 0; i < nums.length; i++) {
 	if (nums[i] != i+1) {
 		list.add(i+1);
 	}
 }
 return list;
 }
}