#ifndef INTEGER_SEQUENCE_HPP
#define INTEGER_SEQUENCE_HPP

#include <cassert>
#include <cstdlib>
#include <new>

class IntegerSequence {
   public:
      IntegerSequence() : data{nullptr}, size{0}, allocated{0} {
      }
      void add(int value) {
	 if (size == allocated) {
	    std::size_t newsize = allocated * 2 + 8;
	    int* newdata = static_cast<int*>(std::realloc(data,
	       newsize * sizeof(int)));
	    if (!newdata) {
	       throw std::bad_alloc();
	    }
	    data = newdata;
	    allocated = newsize;
	 }
	 data[size++] = value;
      }
      std::size_t length() const {
	 return size;
      }
      int& operator()(std::size_t index) {
	 assert(index < size);
	 return data[index];
      }
      const int& operator()(std::size_t index) const {
	 assert(index < size);
	 return data[index];
      }
   private:
      int* data;
      std::size_t size;
      std::size_t allocated;
};

#endif