• Question
• Solution

Question

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.

Solution

Result: Accepted Time: 12 ms

Here should be some explanations.

class Solution {
public:
    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
        unordered_set<int> st(nums1.begin(),nums1.end());
        vector<int> ret;
        for(const auto & x:nums2)
            if(st.count(x))
            {
                ret.push_back(x);
                st.erase(x);
            }
        return std::move(ret);
    }
};

Complexity Analytics

• Time Complexity: $O(n)$
• Space Complexity: $O(n)$