LC 349. Intersection of Two Arrays

题目描述

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

Example 1:

Input: nums1 = [1,2,2,1], nums2 = [2,2]
Output: [2]

Example 2:

Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4]
Output: [9,4]

Note:

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

参考答案

 class Solution {
 public:
     vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {

         unordered_set<int> hashset(nums1.begin(),nums1.end());
         vector<int> res;
         for(auto & i :nums2){ // 提取所有的2
             if(hashset.count(i)){ // 拿2去找 1
                 res.push_back(i);
                 hashset.erase(i); // 比对完了，就把1里面的给删除吧
             }
         }
         return res;
     }
 };