349.cpp

// hash.cpp
class Solution {
public:
  vector<int> intersection(vector<int> &nums1, vector<int> &nums2) {
    unordered_map<int, int> map;
    vector<int> res;
    for (int i = 0; i < nums1.size(); ++i)
      map[nums1[i]] = 1;
    for (int i = 0; i < nums2.size(); map[nums2[i]] = 0, ++i)
      if (map[nums2[i]] == 1)
        res.push_back(nums2[i]);
    return res;
  }
};