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.

找出交集，元素不能重复

---

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set也可以通过