（7）数据结构-基本队列实现

1、简介

定义：一种先进先出的线性表。
队空：front == rear
假队满 rear == MaxSize

2、数据结构

#define MaxSize 50
#define Error -1
typedef struct{
    ElemType Data[MaxSize];
    int front,rear;
}SqQueue;

3、基本操作

SqQueue InitQueue(SqQueue Q);
bool Empty(SqQueue Q);
bool EnQueue(SqQueue &Q,int x);
bool DeQueue(SqQueue &Q, int &x);
ElemType GetTop(SqQueue Q);

3.1 初始化队列

//初始化队列
SqQueue InitQueue(SqQueue Q){
    Q.front = Q.rear = 0;
    return Q;
}

3.2 判断队空

//判断是否Empty
bool Empty(SqQueue Q){
    if (Q.front == Q.rear && Q.front == 0){
        return true;
    }
    return false;
}

3.3 入队

先入队，在让尾指针加一

//入队
bool EnQueue(SqQueue &Q,int x){
    if(Q.rear == MaxSize){
        cout << "Queue is \'full\' " << endl;
        return false;
    }else{
        Q.Data[Q.rear++] = x;
        return true;
    }

}

3.4 出队

//出队
bool DeQueue(SqQueue &Q, int &x){
    if(!Empty(Q)){
        x = Q.Data[Q.front++];
        return true;
    }else{
        cout << "Queue is empty" << endl;
        return false;
    }
}

3.5 获取队头元素

//获取队头元素
ElemType GetTop(SqQueue Q){
    if(!Empty(Q)){
        return Q.Data[Q.front];
    }else{
        cout << "Queue is Empty" << endl;
        return Error;
    }

}

4、完整代码

#include<iostream>
using namespace std;

typedef int ElemType;

#define MaxSize 50
#define Error -1
typedef struct{
    ElemType Data[MaxSize];
    int front,rear;
}SqQueue;

SqQueue InitQueue(SqQueue Q);
bool Empty(SqQueue Q);
bool EnQueue(SqQueue &Q,int x);
bool DeQueue(SqQueue &Q, int &x);
ElemType GetTop(SqQueue Q);
int main(){
    SqQueue Q = InitQueue(Q);
    cout << Q.front << " " << Q.rear << endl;

    cout << "Enqueue" << endl;
    if(EnQueue(Q,10)){
        cout << GetTop(Q) << endl;
    }
    EnQueue(Q,12);


    cout << "Dequeue " << endl;
    int x;
    if(DeQueue(Q,x)){
        cout << x << endl;
    }

    cout << "One more time " << endl;
    int y;
    DeQueue(Q,y);
    cout << y << endl;


    return 0;
}

//初始化队列
SqQueue InitQueue(SqQueue Q){
    Q.front = Q.rear = 0;
    return Q;
}

//判断是否Empty
bool Empty(SqQueue Q){
    if (Q.front == Q.rear && Q.front == 0){
        return true;
    }
    return false;
}

//入队
bool EnQueue(SqQueue &Q,int x){
    if(Q.rear == MaxSize){
        cout << "Queue is \'full\' " << endl;
        return false;
    }else{
        Q.Data[Q.rear++] = x;
        return true;
    }

}

//获取队头元素
ElemType GetTop(SqQueue Q){
    if(!Empty(Q)){
        return Q.Data[Q.front];
    }else{
        cout << "Queue is Empty" << endl;
        return Error;
    }

}

//出队
bool DeQueue(SqQueue &Q, int &x){
    if(!Empty(Q)){
        x = Q.Data[Q.front++];
        return true;
    }else{
        cout << "Queue is empty" << endl;
        return false;
    }
}