Given two arrays, write a function to compute their intersection.

Example:

Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2].

Note:

• • Each element in the result must be unique.
  • The result can be in any order.

 

求两个集合的交集  结果元素必须唯一

 

C++（6ms）：

1 class Solution { 2 public: 3     vector
     
       intersection(vector
      
       & nums1, vector
       
        & nums2) { 4         unordered_set
        
          s(nums1.begin(),nums1.end()) ; 5         vector
         
           ans ; 6         for (int i = 0; i < nums2.size();i++ ){ 7            if(s.count(nums2[i])){ 8               ans.push_back(nums2[i]) ; 9               s.erase(nums2[i]);10            }11         }12         return ans;13     }14 };
         
        
       
      
     

 

java(5ms):

1 class Solution { 2     public int[] intersection(int[] nums1, int[] nums2) { 3         Set
     
       set = new HashSet<>() ; 4         for(int i = 0 ; i < nums1.length ; i++){ 5             set.add(nums1[i]) ; 6         } 7         List
      
        list = new ArrayList<>() ;         8         for(int i : nums2){ 9             if (set.contains(i)){10                 list.add(i) ;11                 set.remove(i) ;12             }13         }14         int[] res = new int[list.size()] ;15         for(int i = 0  ; i < list.size() ; i++){16             res[i] = list.get(i) ;17         }18         return res ;19     }20 }