用两个栈模拟队列的思想就是“倒水思想”,这里我们用自定义类型模拟出线性表,再用线性表做容器实现栈的数据结构,最后用栈来实现队列,代码如下:
#include<iostream>
#include<string>
#include<cassert>
struct __TrueType//类型萃取
{
bool Get()
{
return true;
}
};
struct __FalseType
{
bool Get()
{
return false;
}
};
template <class _Tp>
struct TypeTraits
{
typedef __FalseType __IsPODType;
};
template <>
struct TypeTraits< bool>
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< char>
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< unsigned char >
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< short>
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< unsigned short >
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< int>
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< unsigned int >
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< long>
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< unsigned long >
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< long long >
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< unsigned long long>
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< float>
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< double>
{
typedef __TrueType __IsPODType;
};
template <>
struct TypeTraits< long double >
{
typedef __TrueType __IsPODType;
};
template <class _Tp>
struct TypeTraits< _Tp*>
{
typedef __TrueType __IsPODType;
};
template <class T>//自定义类型实现线性表
class SeqList
{
public:
SeqList()
:_size(0),
_capacity(10),
_array(new T[_capacity])
{
memset(_array, 0, sizeof(T)*_capacity);
}
SeqList(const T &x)
:_size(1),
_capacity(10),
_array(new T[_capacity])
{
_array[0] = x;
}
SeqList(const SeqList & x)
{
_array = new T[x._size];
my_memcpy(_array, x._array, sizeof(T)*x._size);
_capacity = x._size;
_size = _capacity;
}
void PushBack(const T & x)
{
_CheckCapacity();
_array[_size++] = x;
}
void PushFront(const T & x)
{
_CheckCapacity();
for (size_t i = _size; i > 1; i--)
{
_array[_size] = _array[_size - 1];
}
_size++;
_array[0] = x;
}
void PopBack()
{
_size--;
}
void PopFront()
{
assert(_size);
for (size_t i = 0; i < _size - 1; i++)
{
_array[i] = _array[i + 1];
}
_size--;
}
size_t Size()
{
return _size;
}
SeqList & operator = (SeqList l)
{
swap(_array, l._array);
swap(_size, l._size);
swap(_capacity, l._capacity);
return *this;
}
~SeqList()
{
if (_array)
{
delete[] _array;
}
}
T& operator [] (const size_t t)
{
return _array[t];
}
private:
void _CheckCapacity()
{
if (_size >= _capacity)
{
_capacity *= 3;
T * tmp = new T[_capacity];
memcpy(tmp, _array, sizeof(T)*_capacity);
delete[] _array;
_array = tmp;
}
}
void my_memcpy(T* dst, const T* src, size_t size)
{
if (TypeTraits <T>::__IsPODType().Get())
{
memcpy(dst, src, size*sizeof (T));
}
else
{
for (size_t i = 0; i < size; ++i)
{
dst[i] = src[i];
}
}
}
size_t _size;
size_t _capacity;
T *_array;
};
template <class T,
typename Contianer = SeqList<T> >//适配器实现栈
class Stack
{
public:
void Push(const T & x)
{
_con.PushBack(x);
}
void Pop()
{
_con.PopBack();
}
size_t Size()
{
return _con.Size();
}
bool Empty()
{
return Size() == 0;
}
T&top()
{
return _con[Size() - 1];
}
protected:
Contianer _con;
};
template <class T,
typename container = Stack<T> >//以栈为适配器,实现队列
class Queue
{
public:
bool Empty()
{
return (_InStack.Empty() && _OutStack().Empty());
}
size_t Size()
{
return _InStack.Size() + _OutStack.Size();
}
void Push(const T &x)
{
_InStack.Push(x);
}
void Pop()
{
size_t MoveCount = _InStack.Size() - 1;
for (size_t iCount = MoveCount; iCount > 0; --iCount)
{
T temp = _InStack.top();
_OutStack.Push(temp);
_InStack.Pop();
}
_InStack.Pop();
while (false == _OutStack.Empty())
{
T temp = _OutStack.top();
_InStack.Push(temp);
_OutStack.Pop();
}
}
T& Front()
{
return _InStack.top();
}
T& Back()
{
size_t MoveCount = _InStack.Size() - 1;
for (size_t iCount = MoveCount; iCount > 0; --iCount)
{
T temp = _InStack.top();
_OutStack.Push(temp);
_InStack.Pop();
}
T ret = _InStack.top();
while (false == _OutStack.Empty())
{
T temp = _OutStack.top();
_Instack.Push(temp);
_OutStack.Pop();
}
return ret;
}
void PrintQueue()
{
size_t MoveCount = _InStack.Size();
for (size_t iCount = MoveCount; iCount > 0; --iCount)
{
T temp = _InStack.top();
_OutStack.Push(temp);
_InStack.Pop();
}
while (false == _OutStack.Empty())
{
T temp = _OutStack.top();
_InStack.Push(temp);
cout << "<-" << temp;
_OutStack.Pop();
}
cout << endl;
}
private:
container _InStack;
container _OutStack;
};
测试用例如下:
void Test()
{
Queue<int> q1;
q1.Push(1);
q1.Push(2);
q1.Push(3);
q1.Push(4);
q1.Push(5);
q1.Push(6);
q1.PrintQueue();
q1.Pop();
q1.PrintQueue();
}
如有什么不足或疑问,希望指教
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