栈的连续与链式实现

STL中已经有<stack>和<queue>了，写在这里是帮助理解这两种数据结构。

栈：只能在表的一段插入(push)或者删除(pop)，且满足先进先出的顺序。很形象的称之为“栈”。

连续栈（数组实现）：

#include <iostream>using namespace std;const int stackSize = 10000;template <class Stack_entry>class Stack{     // Contiguous Stackpublic:Stack();void pop();             /*pre: make sure the stack is not empty */Stack_entry top() const;/*pre: make sure the stack is not empty */bool push(const Stack_entry&);bool empty() const;private:Stack_entry entry[stackSize];unsigned int count;};template <class Stack_entry>Stack<Stack_entry> :: Stack(){count = 0;}template <class Stack_entry>void Stack<Stack_entry> :: pop(){if(count > 0){count--;}/*else underflow*/return;}template <class Stack_entry>Stack_entry Stack<Stack_entry> :: top() const{ if(count > 0){return entry[count-1]; } /* return underflow */}template <class Stack_entry>bool Stack<Stack_entry> :: push(const Stack_entry& newEntry){if(count < stackSize){entry[count++] = newEntry;return true;}return false/*overflow*/;}template <class Stack_entry>bool Stack<Stack_entry> :: empty() const{return count == 0;}int main(){Stack<int> s;s.push(1);s.push(2);s.push(3);while(!s.empty()){cout << s.top() << endl;s.pop();}return 0;}

链式栈（链表）：

#include <iostream>using namespace std;template <typename Node_entry>struct Node{Node_entry entry;Node* next;Node(){next = NULL;}Node(const Node_entry& newEntry, Node* add_on = NULL){entry = newEntry;next = add_on;}};template <class Stack_entry>class Stack{     // Linked Stackpublic:Stack();Stack(const Stack& original);~Stack();void pop();             /*pre: make sure the stack is not empty */Stack_entry top() const;/*pre: make sure the stack is not empty */void push(const Stack_entry&);bool empty() const;//Stack& operator=(const Stack& original);//private:Node<Stack_entry>* top_node;};template <class Stack_entry>Stack<Stack_entry> :: Stack(){top_node = NULL;}template <class Stack_entry>Stack<Stack_entry> :: Stack(const Stack& original){Node<Stack_entry> *new_copy, *original_node = original.top_node;if(original_node == NULL) top_node = NULL;else{top_node = new_copy = new Node<Stack_entry>(original_node->entry);while(original_node->next != NULL){original_node = original_node->next;new_copy->next = new Node<Stack_entry>(original_node->entry);new_copy = new_copy->next;}}}template <class Stack_entry>Stack<Stack_entry> :: ~Stack(){while(top_node != NULL){Node<Stack_entry>* old_node = top_node;top_node =  top_node -> next;delete old_node;}}template <class Stack_entry>void Stack<Stack_entry> :: pop(){if(top_node != NULL){Node<Stack_entry>* old_node = top_node;top_node =  top_node -> next;delete old_node;}/*else underflow*/return;}template <class Stack_entry>Stack_entry Stack<Stack_entry> :: top() const{ if(top_node != NULL){return top_node -> entry; } /* return underflow */}template <class Stack_entry>void Stack<Stack_entry> :: push(const Stack_entry& newEntry){Node<Stack_entry>* new_top = new Node<Stack_entry>(newEntry, top_node);//if(new_top == NULL) return/*overflow*/;   // the dynamic memory is exhaustedtop_node = new_top;return;}template <class Stack_entry>bool Stack<Stack_entry> :: empty() const{return top_node == NULL;}template <class Stack_entry>Stack<Stack_entry>& Stack<Stack_entry> :: operator=(const Stack<Stack_entry>& original){/*Node *new_top, *new_copy, *original_node = original.top_node;if(original_node == NULL) new_top = NULL;else{new_top = new_copy = new Node(original_node->entry);while(original_node->next != NULL){original_node = original_node->next;new_copy->next = new Node(original_node->entry);new_copy = new_copy->next;}}while(top_node != NULL) pop();top_node = new_top;return *this;*/while(top_node != NULL) pop();Node<Stack_entry> *new_copy, *original_node = original.top_node;if(original_node == NULL) top_node = NULL;else{top_node = new_copy = new Node<Stack_entry>(original_node->entry);while(original_node->next != NULL){original_node = original_node->next;new_copy->next = new Node<Stack_entry>(original_node->entry);new_copy = new_copy->next;}}return *this;}int main(){Stack<int> s;s.push(1);s.push(2);s.push(3);s.pop();cout << "s " << s.top() << endl;Stack<int> t(s);while(!t.empty()){cout << t.top() << endl;t.pop();}return 0;}