349 Intersection of Two Arrays

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.

class Solution {public:    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {        unordered_set<int> m(nums1.begin(), nums1.end());        vector<int> res;        for (auto a : nums2)            if (m.count(a)) {                res.push_back(a);                m.erase(a);            }        return res;    }};

用两个hash表进行查找即可。