Find_the_diff_of_two_arrays.java

// Given two 0-indexed integer arrays nums1 and nums2, return a list answer of size 2 where:

// answer[0] is a list of all distinct integers in nums1 which are not present in nums2.
// answer[1] is a list of all distinct integers in nums2 which are not present in nums1.
// Note that the integers in the lists may be returned in any order.

// Example 1:

// Input: nums1 = [1,2,3], nums2 = [2,4,6]
// Output: [[1,3],[4,6]]
// Explanation:
// For nums1, nums1[1] = 2 is present at index 0 of nums2, whereas nums1[0] = 1 and nums1[2] = 3 are not present in nums2. Therefore, answer[0] = [1,3].
// For nums2, nums2[0] = 2 is present at index 1 of nums1, whereas nums2[1] = 4 and nums2[2] = 6 are not present in nums2. Therefore, answer[1] = [4,6].
// Example 2:

// Input: nums1 = [1,2,3,3], nums2 = [1,1,2,2]
// Output: [[3],[]]
// Explanation:
// For nums1, nums1[2] and nums1[3] are not present in nums2. Since nums1[2] == nums1[3], their value is only included once and answer[0] = [3].
// Every integer in nums2 is present in nums1. Therefore, answer[1] = [].
 

// Constraints:

// 1 <= nums1.length, nums2.length <= 1000
// -1000 <= nums1[i], nums2[i] <= 1000


class Solution {
    public List<List<Integer>> findDifference(int[] nums1, int[] nums2) {
        List<Integer> list1 = new ArrayList<>();
        List<Integer> list2 = new ArrayList<>();

        HashSet<Integer> set = new HashSet<>();
         HashSet<Integer> set2 = new HashSet<>();

         for(int num : nums1){
            set.add(num);
         }

         for(int num : nums2){
             set2.add(num);
         }

         for(int num : set){
           if(!set2.contains(num)){
               list1.add(num);
            }
         }

         for(int num : set2){
            if(!set.contains(num)){  
                list2.add(num);
            }
         }

         List<List<Integer>> result = new ArrayList<>();
         result.add(list1);
         result.add(list2);
         return result;
    }
}