leetcode 349. Intersection of Two Arrays

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.

思路：哈系表（set，map），排序+双指针

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