intersection_349.cpp

#include<unordered_set>
#include <iostream>
#include <vector>
using namespace std;

class Solution {
public:
    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
        unordered_set<int> set1, set2;
        for (auto num : nums1) {
            set1.insert(num);
        }
        for (auto num : nums2) {
            set2.insert(num);
        }
        return getIntersection(set1, set2);
    }

    vector<int> getIntersection(unordered_set<int>& set1, unordered_set<int>& set2) {
        if (set1.size() > set2.size()) {
            return getIntersection(set2, set1);
        }
        vector<int> intersection;
        for (auto num : set1) {
            if (set2.count(num)) {
                intersection.push_back(num);
            }
        }
        return intersection;
    }
};

int main(){
    vector<int> nums1;
    vector<int> nums2;
    nums1.push_back(1);
    nums1.push_back(2);
    nums1.push_back(2);
    nums1.push_back(1);
    nums2.push_back(2);
    nums2.push_back(2);

    Solution sol;
    sol.intersection(nums1, nums2);

}