Two Sum

src/s1_two_sum.cpp

@@ -0,0 +1,14 @@
+#include "s1_two_sum.hpp"
+using namespace std;
+
+vector<int> Solution::twoSum(vector<int>& nums, int target) {
+  unordered_map<int, int> hashtable;
+  for (int i = 0; i < nums.size(); ++i) {
+    auto it = hashtable.find(target - nums[i]);
+    if (it != hashtable.end()) {
+      return {it->second, i};
+    }
+    hashtable[nums[i]] = i;
+  }
+  return {};
+}