以前，我們實現一個棧，輕輕松松，無需考慮太多因素，即可實現。
現在，要求在一個數組里實現兩個棧，那么在數組里怎么實現棧呢？
無非就是下標索引，方法也不局限一種，例如：用奇數下標作為棧s1的結構，用偶數作為s2的結構；再者：一前一后的結構，棧s1從前往后，棧s2從后往前。
#include <iostream>
using namespace std;
template <class T>
class arrayWithTwoStack
{
public:
arrayWithTwoStack(int size)
: top1(-1)
, top2(-1)
, _size(size)
{
_array = new T[size + 1];
}
~arrayWithTwoStack()
{
if (_array)
{
delete[] _array;
}
}
public:
void Push(int index, T data)
{
if (_size % 2 == 0)
{
if ((top1 > _size - 2) || (top2 >= _size - 1))
{
cout << "Stack is overflow!" << endl;
return;
}
}
else
{
if ((top1 > _size - 1) || (top2 >= _size - 2))
{
cout << "Stack is overflow!" << endl;
return;
}
}
0是一號棧， 1是二號棧
if (index == 0)
{
if (top1 == -1)
{
top1 = 0;
_array[top1] = data;
}
else
{
top1 += 2;
_array[top1] = data;
}
}
if (index == 1)
{
if (top2 == -1)
{
top2 = 1;
_array[top2] = data;
}
else
{
top2 += 2;
_array[top2] = data;
}
}
}
T Pop(int index)
{
int ret;
if (index == 0)
{
if (top1 < 0)
{
return -1;
cout << "Stack is underflow!" << endl;
}
else
{
ret = _array[top1];
top1 -= 2;
}
}
if (index == 1)
{
if (top2 < 1) // top2從下標為1開始
{
return -1;
cout << "Satck is underflow!" << endl;
}
else
{
ret = _array[top2];
top2 -= 2;
}
}
return ret;
}
T top(int index) // 返回棧頂元素
{
if (index == 0 && top1 >= 0)
{
return _array[top1];
}
if (index == 1 && top2 >= 1)
{
return _array[top2];
}
cout << "No Top!" << endl;
exit(0);
}
bool isEmpty(int index)
{
if (index == 0 && top1 < 0)
return false;
if (index == 1 && top2 < 1)
return false;
return true;
}
void Show()
{
if (top1 < 0 && top2 < 1)
{
cout << "Stack has no data!" << endl;
return;
}
else
{
for (int i = 0; i < _size; i++)
cout << _array[i] << " ";
}
cout << endl;
}
private:
T top1;
T top2;
int _size;
T* _array;
};
int main()
{
arrayWithTwoStack<int> s(10);
s.Push(0, 0);
s.Push(0, 2);
s.Push(0, 4);
s.Push(1, 1);
s.Push(1, 3);
s.Push(1, 5);
s.Push(1, 7);
s.Push(0, 6);
s.Push(0, 8);
s.Push(1, 9);
s.Push(0, 10);
s.Show();
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(0) << endl;
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << endl;
cout << s.top(0) << endl;
cout << s.top(1) << endl;
s.Pop(0);
cout << (s.isEmpty(0) ? "Yes" : "No") << endl;
cout << (s.isEmpty(1) ? "Yes" : "No") << endl;
system("pause");
return 0;
}
若有紕漏，歡迎指正。
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