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Stack.h
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Stack.h
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#ifndef STACK_H_
#define STACK_H_
#define DEFAULT_CAPACITY 3
typedef int Rank;
template <typename T>
class Stack
{
private:
T *_elem;
Rank _size;
Rank _capacity;
public:
Stack(int n = 0,T ele = 0){
_elem = new T[_capacity = DEFAULT_CAPACITY << 1];
for(_size = 0;_size < n;_size++)
_elem[_size] = ele;
expand();
};
~Stack(){delete [] _elem;};
void expand();
void shrink();
bool empty(){return (_size == 0);}
Rank size(){return _size;}
void push(T const&e);
T pop();
T & top();
};
template <typename T>
void Stack<T>::expand(){
if(_size < _capacity) return;
if(_capacity < DEFAULT_CAPACITY) _capacity = DEFAULT_CAPACITY;
T *oldelem = _elem;
_elem = new T[_capacity <<= 1];
for(int i = 0;i < _size; ++i){
_elem[i] = oldelem[i];
}
delete [] oldelem;
}
template <typename T>
void Stack<T>::shrink(){
if(_capacity < DEFAULT_CAPACITY << 1) return;
if(_size << 2 > _capacity) return;
T *oldelem = _elem;
_elem = new T[_capacity >>= 1];
for(int i = 0;i < _size; ++i){
_elem[i] = oldelem[i];
}
delete [] oldelem;
}
template <typename T>
void Stack<T>::push(T const&e){
expand();
_elem[_size++] = e;
}
template <typename T>
T Stack<T>::pop(){
shrink();
return _elem[_size-- - 1];
}
template <typename T>
T & Stack<T>::top(){
return _elem[_size - 1];
}
#endif