leetcode

difference-of-two-arrays.dart (1033B)

---

 //Find all unique values that appear in one list but not the other
 //then return the unique values as two lists.
 //I used a hashmap for this when I should have used a set because 
 //I only need to know unique values and not how many of each there are.
 //The time complexity of this code is O(n + k) where n is the number of elements
 //in the first list and k is the number in the second. 
 //Time: 375ms Beats: 30%
 //Memory: 150.5MB Beats: 60%
 
 class Solution {
   List<List<int>> findDifference(List<int> nums1, List<int> nums2) {
       Map<int , int> map1 = {};
       Map <int, int> map2 = {};
       for(int i = 0 ; i < nums1.length ; ++i){
           map1[nums1[i]] = (map1[nums1[i]] ?? 0) + 1;
       }
       for(int i = 0 ; i < nums2.length ; ++i){
           map2[nums2[i]] = 1;
       }
       for(int i = 0 ; i < nums1.length ; ++i){
           map2.remove(nums1[i]);
       }
       for(int i = 0 ; i < nums2.length ; ++i){
           map1.remove(nums2[i]);
       }
       
       return [map1.keys.toList() , map2.keys.toList()];
   }
 }