Hash Table -- Leetcode problem350. Intersection of Two Arrays II

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

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

Note:
Each element in the result should appear as many times as it shows in both arrays.
The result can be in any order.

• 分析：这道题和349.Intersection of Two Arrays比较相似，唯一不同是这道题要输出所有重复的情况，输出有重复。
• 思路一：用unorder_map在Intersection of Two Arrays基础上进行修改就可以通过测试。

class Solution {public:    vector<int> intersect(vector<int>& nums1, vector<int>& nums2) {    vector<int> my_vec;    unordered_map<int, int> my_map;    for (int i = 0; i < nums1.size(); i++) {        my_map[nums1[i]]++;    }    for (int i = 0; i < nums2.size(); i++) {        if (my_map.find(nums2[i]) != my_map.end() && --my_map[nums2[i]] >= 0) {            my_vec.push_back(nums2[i]);        }    }    return my_vec;}};