Problem no. 448.java

// Ques : find all disappeared numbers in an array


// Ques Link : https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/


package com.nitin;

import java.util.*;

public class FindAllMissing {
    public static void main(String[] args) {
        int[] nums = {4,3,2,7,8,2,3,1};

        ArrayList<Integer> list = new ArrayList<>(100);
        System.out.println(findDisappearedNumbers(nums));

    }
    
        public static  List<Integer> findDisappearedNumbers(int[] nums) {
            int i = 0;
            while (i < nums.length) {
                int correct = nums[i] - 1;
                if (nums[i] != nums[correct]) {
                    swap(nums, i, correct);
                } else {
                    i++;
                }
        }

        // just find missing numbers
        List<Integer> ans = new ArrayList<>();
        for (int index = 0; index < nums.length; index++) {
            if (nums[index] != index + 1) {
                ans.add(index + 1);
            }
        }

        return ans;
    }

    static void swap(int[] nums, int first, int second) {
        int temp = nums[first];
        nums[first] = nums[second];
        nums[second] = temp;
    }
}