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Vector.cpp
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Vector.cpp
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template<typename T>
class Vector {
private:
T *begin_;
size_t size_, elements_;
static const size_t BASE_ = 2;
public:
Vector() : size_(1), begin_(new T[1]), elements_(0) {}
~Vector() { delete[] begin_; }
void push_back(T value) {
if (elements_ < size_)
begin_[elements_++] = value;
else {
T *new_begin = new T[size_ * BASE_];
for (size_t i = 0; i < elements_; ++i)
new_begin[i] = begin_[i];
std::swap(new_begin, begin_);
delete[] new_begin;
size_ *= BASE_;
begin_[elements_++] = value;
}
}
T pop_back() {
T ret = begin_[--elements_];
if (elements_ <= size_ / BASE_) {
T *new_begin = new T[size_ / BASE_];
for (size_t i = 0; i < elements_; ++i)
new_begin[i] = begin_[i];
std::swap(new_begin, begin_);
delete[] new_begin;
size_ /= BASE_;
}
return ret;
}
T &back() { return begin_[elements_ - 1]; }
const T &back() const { return begin_[elements_ - 1]; }
size_t size() const { return elements_; }
T &operator[](int n) { return begin_[n]; }
const T &operator[](int n) const { return begin_[n]; }
void clear() {
size_ = 1;
delete[] begin_;
begin_ = new T[1];
elements_ = 0;
}
}