LC 349. Intersection of Two Arrays

Title Description

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.

Answers

 1 class Solution {
 2 public:
 3     vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
 4         
 5         unordered_set<int> hashset(nums1.begin(),nums1.end());
 6         vector<int> res;
 7         for(auto & i :nums2){ // 提取所有的2
 8             if(hashset.count(i)){ // 拿2去找 1
 9                 res.push_back(i);  
10                 hashset.erase(i); // match finished, put inside a bar deleted 
. 11              }
 12 is          }
 13 is          return RES;
 14      }
 15 };