chore(cpp): rework reading collections

Signed-off-by: Matej Focko <mfocko@redhat.com>

.common/cpp/skeleton.cpp

@@ -131,17 +131,22 @@ decltype(auto) y_combinator(Fun &&fun) {
 #pragma endregion /* functional */
 
 #pragma region input
-template <typename T>
-std::vector<T> load_vector(std::size_t size) {
-  std::vector<T> result{};
+template <typename Container>
+void collect(Container &c, std::size_t size) {
+  auto it = std::inserter(c, c.begin());
 
   for (auto i = 0u; i < size; ++i) {
-    T x;
+    typename Container::value_type x;
     std::cin >> x;
-    result.push_back(std::move(x));
+    it = std::move(x);
   }
+}
 
-  return result;
+template <typename Container>
+Container collect(std::size_t size) {
+  Container c{};
+  collect(c, size);
+  return c;
 }
 #pragma endregion /* input */