leetcode 349. Intersection of Two Arrays

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

Example 1:

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

Example 2:

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

Note:

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

思路：哈系表（set，map），排序+双指针

 1 class Solution {
 2 public:
 3     vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
 4         unordered_set<int> s(nums1.begin(), nums1.end());
 5         vector<int> res;
 6         for (int x : nums2) {
 7             if (s.erase(x)) {
 8                 res.push_back(x);
 9             }
10         }
11         return res;
12     }
13 };