[数据结构][队列]链表模拟队列操作

#include<iostream>
#include<cstdio>
using namespace std;

#define MAXSIZE 100

typedef int Status;
typedef int Elem;

typedef struct QNode
{
  /* data */
  Elem data;
  struct QNode *next;

}QNode, *QueuePtr;

typedef struct
{
  QueuePtr front;
  QueuePtr rear;
}LinkQueue;//这种写法让我想起了 定义结构体 然后定义类 在类里放结构体 

Status InitQueue(LinkQueue &Q)
{
  Q.front = Q.rear = new QNode;
  Q.front->next = NULL; //头指针 空

  return 1;
}

Status EnQueue_H(LinkQueue &Q, Elem e)
{
  QNode *p = new QNode;
  p->data = e;
  p->next = NULL;

  Q.rear->next = p;//队尾的结点指向 新节点p
  Q.rear = p;//队尾为p

  return 1;
}

Status DeQueue(LinkQueue &Q, Elem &e)
{
  if (Q.rear == Q.front) return 0;

  QNode *p = Q.front->next;
  e = p->data;

  Q.front->next = p->next; //其实就是往下走 当删除了

  if (Q.rear == p) Q.rear = Q.front; //如果整个没了 那就尾巴指向头

  delete p;

  return 1;
}

Elem GetHead(LinkQueue &Q)
{
  if (Q.front != Q.rear)
    return Q.front->next->data;

  return 0;
}

int main()
{

  LinkQueue Q;
  
  //1
  InitQueue(Q);

  //1
  EnQueue_H(Q, 1);
  cout << GetHead(Q);

  //1
  Elem e = 0;
  DeQueue(Q, e);
  cout << GetHead(Q);

  return 1;
}