Add improved code

Author: colorbox

349/step2_1_fix.cpp

@@ -0,0 +1,17 @@
+class Solution {
+public:
+  vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
+    map<int, int> num_to_count;
+    for (int num : nums1) {
+      num_to_count[num]++;
+    }
+    vector<int> intersected_nums;
+    for(int num : nums2) {
+      if (num_to_count[num] > 0) {
+        intersected_nums.push_back(num);
+        num_to_count[num] = 0;
+      }
+    }
+    return intersected_nums;
+  }
+};

349/step2_3_fix.cpp

@@ -0,0 +1,10 @@
+class Solution {
+public:
+  vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
+    set<int> set1(nums1.begin(), nums1.end());
+    set<int> set2(nums2.begin(), nums2.end());
+    vector<int> intersected_nums;
+    std::set_intersection(set1.begin(), set1.end(), set2.begin(), set2.end(), std::inserter(intersected_nums, intersected_nums.end()));
+    return intersected_nums;
+  }
+};