用两个栈模拟一个队列

来源：互联网发布：java 线程间通信编辑：程序博客网时间：2024/05/17 01:11

思路：

让栈A提供入队功能，栈B提供出队功能。

入队列：栈A。

出队列：如果栈B不为空，直接弹出栈B的栈顶数据；如果栈B为空，则依次弹出栈A的数据，放入栈B中，再弹出栈B的栈顶数据。

方法一：

#include<iostream>#include<stack>#include<string>using namespace std; template<class T>struct MyQueue{      void Enqueue(T t)      {            s1.push(t);      }       T Dequeue()      {            if(s2.empty())            {                  if(0 == s1.size())                  {                       exit(1);                  }                   while(!s1.empty())                  {                       s2.push(s1.top());                       s1.pop();                  }            }                       T retVal = s2.top();            s2.pop();            return retVal;      }       stack<T> s1;      stack<T> s2;}; intmain(){      MyQueue<int> mq;      int begin = 0;      int end = 10;      int i;       for(i = begin; i < end; i++)      {            mq.Enqueue(i);      }       for(i = begin; i < end; i++)      {            cout<<mq.Dequeue()<<' ';      }      cout<<endl;       MyQueue<float> mq2;      mq2.Enqueue(1.1f);      mq2.Enqueue(2.2f);      cout << mq2.Dequeue() << endl;       MyQueue<string> mq3;      string s1 = "hello";      string s2 = "world";      mq3.Enqueue(s1);      mq3.Enqueue(s2);      cout << mq3.Dequeue() << endl;       return 0;}

运行结果：

01 2 3 4 5 6 7 8 9

1.1

hello

Pressany key to continue

方法二：

#include <iostream>using namespace std;struct Node{public:Node(int i):data(i),next(NULL){}int data;Node *next;};class Stack{public:Stack():top(NULL){}void Push(Node node);//入栈int Pop();//出栈bool IsEmpty();//是否为空void Print();//打印所有元素private:Node *top;};void Stack::Push(Node node){Node *n = new Node(node.data);n->next = top;top = n;}int Stack::Pop(){if (IsEmpty()){cout << "Stack Empty!" << endl;exit(1);}else{int topVal = top->data;Node *temp = top;top = top->next;delete temp;return topVal;}}bool Stack::IsEmpty(){if (NULL == top){return 1;}else{return 0;}}void Stack::Print(){if(IsEmpty()){cout << "Inner Stack Empty!" << endl;}else{Node *node = top;while (node != NULL){cout << node->data << " ";node = node->next;}cout << endl;}}class Queue{public:void Enqueue(Node node);//入队int Dequeue();//出队bool IsEmpty();//是否为空private:Stack s1;//用于入队Stack s2;//用于出队};void Queue::Enqueue(Node node){s1.Push(node);//只对s1进行进栈操作cout << "Enqueue " << node.data << endl;}int Queue::Dequeue(){if(s2.IsEmpty()){if(s1.IsEmpty())//s2和s1都为空{cout << "Queue Empty! Can not be dequeued again!" << endl;exit(1);}else//s2为空s1不为空，把s1的所有元素都倒入s2中{while(!s1.IsEmpty()){int i = s1.Pop();s2.Push(Node(i));}}}return s2.Pop();}bool Queue::IsEmpty(){if (s1.IsEmpty() && s2.IsEmpty()){return 1;}else{return 0;}}int main(){Queue q;q.Enqueue(Node(1));q.Enqueue(Node(2));q.Enqueue(Node(3));cout << "Dequeue " << q.Dequeue() << endl;q.Enqueue(Node(4));cout << "Dequeue " << q.Dequeue() << endl;cout << "Dequeue " << q.Dequeue() << endl;cout << "Dequeue " << q.Dequeue() << endl;return 0;}

运行结果：

Enqueue1

Enqueue2

Enqueue3

Dequeue1

Enqueue4

Dequeue2

Dequeue3

Dequeue4

Pressany key to continue

0 0