MyVector

#include <iostream>

using namespace std;

// Вектор целых чисел.
class MyVector {
 public:
  int operator[](int i) { return buffer[i]; }
  void PushBack(int x) {
    if (size == capacity) Grow();
    buffer[size++] = x;
  }
  int Size() { return size; }
 private:
  int size = 0;
  int capacity = 0;
  int* buffer = nullptr;

  void Grow() {
    int new_capacity = max(capacity * 2, 1);
    int* new_buffer = new int[new_capacity];
    for (int i = 0; i < size; ++i) new_buffer[i] = buffer[i];
    delete[] buffer;
    buffer = new_buffer;
    capacity = new_capacity;
  }
};

int main() {
  MyVector v;
  v.PushBack(5);
  v.PushBack(10);
  v.PushBack(11);
  v.PushBack(15);
  v.PushBack(17);
  for (int i = 0; i < v.Size(); ++i)
    cout << v[i] << " ";
  return 0;
}