数据结构面试之三——栈的常见操作
题注：《面试宝典》有相关习题，但思路相对不清晰，排版有错误，作者对此参考相关书籍和自己观点进行了重写，供大家参考。
三、栈的基本操作
3.1用数组构造栈
【注意以下几点】：
1.基于数组的栈的三要素：1）栈的最大容量maxSize; 2)栈的当前容量=当前栈中元素的个数=栈顶top-1；3）动态数组存储栈的元素 Type* list；
2.对于出栈、入栈的操作要对应先判断栈空、栈满；如果空、满要有异常处理或错误提示。
3.注意入栈push操作，先入栈后top+1；出栈pop则相反，先top-1，再出栈。【注意因为，top指向数组中最后一个元素的下一个位置】。
4.拷贝构造函数和赋值函数要注意，尤其赋值的时候，避免自身赋值、同时要注意大小不一致的不能完成赋值操作，要有相关提示。
template<typenameType>
class arrStack
{
public:
arrStack(intnSize=100);
~arrStack();
arrStack(constarrStack& copyStack);
arrStack&operator=(const arrStack& otherStack);
voidinitializeStack();
void destroyStack();
bool isStackEmpty();
bool isStackFull();
void push(constType& item);
void pop(Type&poppedItem);
private:
int maxSize;
int top;
Type* list;
};
template<typename Type>
arrStack<Type>::arrStack(int nSize=100)
{
if(nSize < 0)
{
nSize = 100;
list = newType[nSize];
top = 0;
maxSize = 100;
}
else
{
list = newType[nSize];
top = 0;
maxSize =nSize;
}
}
template<typename Type>
arrStack<Type>::~arrStack()
{
if(!list)
{
delete[]list; //注意数组的删除，为delete []list;
list = NULL;
}
}
template<typename Type>
arrStack<Type>::arrStack(const arrStack& copyStack)
{
maxSize =copyStack.maxSize;
top = copyStack.top;
list = newType[maxSize]; //注意需要自定义大小,容易出错.
for( int i = 0; i <top; i++)
{
list[i] =copyStack.list[i];
}
}
template<typename Type>
arrStack<Type>& arrStack<Type>::operator=(constarrStack& otherStack)
{
if(this ==&otherStack)
{
cout <<"can't copy oneSelf!" << endl;
return *this;
}
else
{
if(maxSize !=otherStack.maxSize)
{
cout<< "The Size of two stack are not equal!" << endl;
return*this;
}
else
{
maxSize= otherStack.maxSize;
top =otherStack.top;
for( inti = 0; i < top; i++)
{
list[i]= otherStack.list[i];
}//endfor
return*this;
}
}//end else
}
template<typename Type>
void arrStack<Type>::initializeStack()
{
destroyStack();
}
template<typename Type>
void arrStack<Type>::destroyStack()
{
top = 0;
}
template<typename Type>
bool arrStack<Type>::isStackEmpty()
{
return (top == 0);
}
template<typename Type>
bool arrStack<Type>::isStackFull()
{
return (top ==maxSize);
}
template<typename Type>
void arrStack<Type>::push(const Type& item)
{
if(!isStackFull())
{
list[top] =item;
top++;
}
else
{
cout <<"The Stack was already Full!" << endl;
}
}
template<typename Type>
void arrStack<Type>::pop(Type& poppedItem)
{
if(!isStackEmpty())
{
top--;
poppedItem =list[top];
}
else
{
cout <<"The Stack was already Empty!" << endl;
}
}
3.2用链表构造栈
链表构造栈注意：
1） 判断栈空的标记是top==NULL；由于栈的空间可以动态分配，因此可以认为链栈不会满。
2） 栈的入栈Push操作要先判定栈是否已经满，非满才可以入栈。先入栈，再调整top指针；
3） 栈的出栈Pop操作要先判定栈是否已空，非空才可以出栈。先调整top指针，再出栈，并删除原结点。
4） 可以加count判定当前结点的个数。
template<typename Type>
struct nodeType
{
Type info;
nodeType* link;
};
template<typename Type>
class linkedStack
{
public:
linkedStack();
~linkedStack();
linkedStack(constlinkedStack<Type>&);
linkedStack&operator=(const linkedStack<Type>&);
voidinitializeStack();
void destroyStack();
bool isStackEmpty()const;
bool isStackFull()const;
void push(constType& item);
void pop(Type&poppedItem);
void nodeCount();
voidreversePrint(); //逆向打印的非递归实现...
private:
nodeType<Type>*top;
int count; //统计节点个数
};
template<typename Type>
linkedStack<Type>::linkedStack()
{
count = 0;
top = NULL;
}
template<typename Type>
linkedStack<Type>::~linkedStack()
{
while( top != NULL )
{
nodeType<Type>*tempNode = new nodeType<Type>;
tempNode = top;
top =top->link;
deletetempNode;
}//end if
}
template<typename Type>
linkedStack<Type>::linkedStack(constlinkedStack<Type>& copyStack)
{
if(copyStack.top !=NULL)
{
nodeType<Type>*current;
nodeType<Type>*first;
nodeType<Type>*newNode;
top = newnodeType<Type>;
top->info =copyStack.top->info; //此处的top不能直接用，内存报错！
top->link =copyStack.top->link;
first =top; //first跟进当前链表...
current =copyStack.top->link; //current跟进copy链表...
while( current!= NULL)
{
newNode= new nodeType<Type>;
newNode->link= current->link;
newNode->info= current->info;
first->link= newNode;
first =newNode;
current= current->link;
}//end while
count =copyStack.count;
}//end if
else
{
top = NULL;
count = 0;
}
}
template<typename Type>
linkedStack<Type>&linkedStack<Type>::operator=(const linkedStack<Type>&otherStack)
{
//1避免自身赋值
if(this ==&otherStack)
{
cout <<"Can't copy oneself!" << endl;
return *this;
}
//2其他
else
{
if(top != NULL)
{
destroyStack();
}
if(otherStack.top!= NULL)
{
nodeType<Type>*current;
nodeType<Type>*first;
nodeType<Type>*newNode;
top =new nodeType<Type>;
top->info= otherStack.top->info;
top->link= otherStack.top->link;
first =top; //first跟进当前链表...
current= otherStack.top->link; //current跟进copy链表...
while(current != NULL)
{
newNode= new nodeType<Type>;
newNode->link= current->link;
newNode->info= current->info;
first->link= newNode;
first= newNode;
current= current->link;
}//endwhile
count =otherStack.count;
}//end if
else
{
top =NULL;
count =0;
}
return *this;
}
}
template<typename Type>
void linkedStack<Type>::initializeStack()
{
destroyStack();
}
template<typename Type>
void linkedStack<Type>::destroyStack()
{
count = 0;
top = NULL;
}
template<typename Type>
bool linkedStack<Type>::isStackEmpty() const
{
return (count == 0);
}
template<typename Type>
bool linkedStack<Type>::isStackFull() const //空间非固定，动态申请!
{
return false;
}
template<typename Type>
void linkedStack<Type>::push(const Type& item)
{
if(!isStackFull())
{
nodeType<Type>*newNode = new nodeType<Type>;
newNode->info= item;
newNode->link= NULL;
if(top == NULL)
{
top = newNode;
}
else
{
newNode->link= top;
top =newNode;
}
count++;
cout <<item << " was pushed!" << endl;
}
}
template<typename Type>
void linkedStack<Type>::pop(Type& poppedItem)
{
if(!isStackEmpty())
{
nodeType<Type>*temp = new nodeType<Type>;
temp = top;
poppedItem =top->info;
top =top->link;
count--;
cout <<poppedItem << " was popped!" << endl;
delete temp;
}
}
template<typename Type>
void linkedStack<Type>::nodeCount()
{
cout <<"nodeCount = " << count << endl;
}
//上一节的递归实现逆向链表打印，这是非递归的实现。
template<typename Type>
void linkedStack<Type>::reversePrint() //逆向打印的非递归实现...
{
// 注释部分可作为链表调用栈的非递归实现。
// nodeType<Type>*current = new nodeType<Type>;
// current = top;
// while(current != NULL)
// {
// pop(current->info);
// current =current->link;
// }
int poppedItem = 0;
while(!isStackEmpty())
{
pop(poppedItem);
}
