Intersection of Two Arrays

Description

Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must be unique and you may return the result in any order.

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] Explanation: [4,9] is also accepted.

Constraints:

• 1 <= nums1.length, nums2.length <= 1000
• 0 <= nums1[i], nums2[i] <= 1000

Code

Time Complexity: $O(N)$, Space Complexity: $O(N)$

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 n: nums2) {
            if(m.count(n)) {
                res.push_back(n);
                m.erase(n);
            }
        }
 
        return res;
    }
};

Source

• Intersection of Two Arrays - LeetCode