求唯一交集

class Solution {
   public int[] intersection(int[] nums1, int[] nums2) {
         if(nums1 ==null||nums2 ==null){
             return null;
         }
         HashMap<Integer  , Integer> map = new HashMap<>();
         for(int i = 0; i < nums1.length; i++){
                 map.put(nums1[i], map.getOrDefault(nums1[i],0) + 1);
         }
         LinkedList<Integer> list = new LinkedList<Integer>();
         for (int j= 0; j < nums2.length; j++) {
             Integer num=map .get(nums2 [j]) ;
                 if(num!=null){
                    list .add(nums2[j]);
                    map .remove(nums2[j]) ;
                 }
         }
         int count = list.size();
         int[] aux = new int[count];
         for(int i = 0; i < count; i++){
             aux[i] = list.poll();
         }
         return aux;
     }
}