栈和队列3--循环队列（少用1位）

对于循环队列区分是队满还是队空，
有2种解决方法
1.少用1个元素

判空条件：front=rear=0,
判满条件：（Q.rear+1)% MaxSize==Q.front；
入栈：base[rear++]=e;    出栈：e=base[front++];

2.另设一个标志位，加以判断，如下一篇博客

==========================================
本篇结构：

从尾入，从头出

判空条件：front=rear=0,判满条件：（Q.rear+1)% MaxSize==Q.front

入栈：base[rear++]=e; 出栈：e=base[front++];

#include"pch.h"

#include<iostream>
#define//循环队列最大长度
using namespace std;
typedef  int QElemType;//数据类型

typedef struct {
  QElemType *base;//
  int front;//头指针
  int rear;//尾指针
}SqQueue;

//1.初始化,队空条件：front=rear=0
bool InitQueue(SqQueue &Q) {
  //空队列
  Q.base = new QElemType[MaxSize];
  if (!Q.base)  return false;
  Q.front = Q.rear = 0; return true;
}

//解决假溢出问题，1，少用一个元素，判断满的条件：（Q.rear+1)% MaxSize==Q.front  2.设置标志位（暂未定）
//2.入列
bool EnQueue(SqQueue & Q,QElemType e) {
  if ((Q.rear + 1) % MaxSize == Q.front) return false;//循环队满
  Q.base[Q.rear] = e;
  Q.rear = (Q.rear + 1) % MaxSize;//队尾加1
  return true;
}

//3.队长度
int QueueLength(SqQueue Q) {
  return (Q.rear + MaxSize - Q.front) % MaxSize;
}

//4.出队列,删除头元素
bool DeQueue(SqQueue &Q, QElemType &e) {
  if (Q.front == Q.rear)  return false;//判空
  e = Q.base[Q.front];
  Q.front = (Q.front + 1) % MaxSize;
  return true;
}

//5.取头元素
QElemType GetTop(SqQueue Q) {
  if (Q.rear != Q.front)
    return Q.base[Q.front];
}

//6.遍历
void ShowQueue(SqQueue Q) {
  if (Q.front == Q.rear) cout << "队列空" << endl;
  while(Q.front!= Q.rear) {
    cout << Q.base[Q.front] << " ";
    Q.front = (Q.front + 1) % MaxSize;
  }
}

int main() {
  SqQueue  S; QElemType e;
  if (InitQueue(S))cout << "Succeed" << endl;
  else cout << "Failed" << endl;
  //入栈
  cout << "input e:\t";
  while (cin >> e) {//按"ctrl+z"结束输入
    EnQueue(S, e);
    cout << "input e:\t";
  }
  cout << "栈顶元素为" << GetTop(S) << endl;
  cout << "栈所有元素为" << endl;
  ShowQueue(S);
  cout << "栈长度为" << QueueLength(S) << endl;
  //出栈
  if(DeQueue(S, e))
  cout << "移除的头元素是" << e<<endl;
  else cout << "栈空" << endl;
  cout << "栈剩下所有元素为" << endl;
  ShowQueue(S);
  cout << "栈长度为" << QueueLength(S) << endl;
}