Merge pull request kelvins#239 from Riei-Joaquim/feat/two_sum_cpp

Feat/two sum cpp

Author: kelvins

README.md

@@ -3442,8 +3442,8 @@ Com o objetivo de alcançar uma abrangência maior e encorajar mais pessoas a co
                 </a>
             </td>
             <td> <!-- C++ -->
-                <a href="./CONTRIBUTING.md">
-                    <img align="center" height="25" src="./logos/github.svg" />
+                <a href="./src/cpp/TwoSum.cpp">
+                    <img align="center" height="25" src="./logos/cplusplus.svg" />
                 </a>
             </td>
             <td> <!-- Java -->

src/cpp/TwoSum.cpp

@@ -0,0 +1,42 @@
+#include <iostream>
+#include <unordered_map>
+#include <vector>
+
+/*!
+ * \brief Determine whether in the list of retrieved numbers there is a
+ combination of two numbers that resulted in the target sum.
+ *  \return Two indexes of the list whose sum of elements results in the
+ target value
+ */
+std::vector<int> twoSum(std::vector<int> &nums, int target) {
+  std::unordered_map<int, int> mapSum; // val, vect<idx>
+
+  for (int i = 0; i < nums.size(); i++) {
+    int compTarget = target - nums[i];
+
+    if (mapSum.count(compTarget)) {
+      return {i, mapSum[compTarget]};
+    } else {
+      mapSum.insert({nums[i], i});
+    }
+  }
+
+  return {};
+}
+
+int main() {
+  std::vector<int> values{9, 1, 2, 5, 7, 11, 15};
+  int target = 9;
+
+  auto sumIdxFor = twoSum(values, target);
+  if (sumIdxFor.empty()) {
+    std::cout << "no existent values with two sum: " << target << " in array"
+              << std::endl;
+  } else {
+    std::cout << "Two sum for target: " << target << " in array is "
+              << values[sumIdxFor[0]] << " and " << values[sumIdxFor[1]]
+              << std::endl;
+  }
+
+  return 0;
+}