用OC基于数组实现循环队列

一、简言

使用数组实现循环队列时，始终会有一个空余的位置预留着，作为一个判决队列已满的条件(当然也可以采用其他方式)。在前面已经用C++介绍了基本的算法，可以去回顾一下https://www.cnblogs.com/XYQ-208910/p/11700048.html。光说不练嘴把式，现在本文使用OC面向对象的思想来实现一下。

 

二、代码

ArrayQueue

//
//  ArrayQueue.h
//  运行时
//
//  Created by 夏远全 on 2019/10/19.
//

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface ArrayQueue : NSObject

/**
 构造一个循环队列
 @param capacity 队列容量
 @return 队列
 */
+(instancetype)constrcutArrayQueueWithCapacity:(int)capacity;


/**
 入队列
 @param element 元素
 */
-(void)enQueueWithElement:(id)element;


/**
 出队列
 @return 元素
 */
-(id)deQueueElement;


/**
 队列是否为空
 @return 布尔值
 */
-(BOOL)isEmpty;

/**
 队列是否已满
 @return 布尔值
 */
-(BOOL)isFull;

/**
 获取元素个数
 @return 个数
 */
-(int)eleCount;

@end

NS_ASSUME_NONNULL_END

//
//  ArrayQueue.m
//  运行时
//
//  Created by 夏远全 on 2019/10/19.
//

#import "ArrayQueue.h"

@interface ArrayQueue ()
@property (nonatomic, strong) NSMutableArray *array;
@property (nonatomic, assign) int     front;
@property (nonatomic, assign) int     rear;
@property (nonatomic, assign) int     capacity;
@end

@implementation ArrayQueue

/**
 构造一个循环队列
 @param capacity 队列容量
 @return 队列
 */
+(instancetype)constrcutArrayQueueWithCapacity:(int)capacity {
    
    ///断言一下
    assert(capacity>0);
    
    ArrayQueue *arrayQueue = [[ArrayQueue alloc] init];
    arrayQueue.array = [NSMutableArray array]; //初始化容器
    arrayQueue.capacity = capacity;            //初始化容量
    arrayQueue.front = arrayQueue.rear = 0;    //初始化首尾指针
    return arrayQueue;
}


/**
 入队列
 @param element 元素
 */
-(void)enQueueWithElement:(id)element {
    
    ///判断队列是否已满
    if ([self isFull]) {
        NSLog(@"队列已满，元素%@不能被入列, front = %d , rear = %d", element, self.front, self.rear);
        return;
    }
    
    ///插入新元素
    self.array[self.rear] = element;
    
    ///更新队尾指针
    self.rear  = (self.rear + 1) % self.capacity;
    
    NSLog(@"入队列的元素 = %@, front = %d , rear = %d", element, self.front, self.rear);
}


/**
 出队列
 @return 元素
 */
-(id)deQueueElement {
    
    ///判断队列是否已空
    if ([self isEmpty]) {
        NSLog(@"队列已空, front = %d , rear = %d", self.front, self.rear);
        return nil;
    }
    
    ///取出队头的元素
    id element = self.array[self.front];
    
    ///更新队头指针
    self.front = (self.front + 1) % self.capacity;
    
    NSLog(@"出队列的元素 = %@, front = %d , rear = %d", element, self.front, self.rear);
    
    return element;
}


/**
 队列是否为空
 @return 布尔值
 */
-(BOOL)isEmpty {
    
    if (self.front == self.rear) {
        return YES;
    }
    return NO;
}


/**
 队列是否已满
 @return 布尔值
 */
-(BOOL)isFull {
    
    if (self.front == (self.rear + 1) % self.capacity) {
        return YES;
    }
    return NO;
}

/**
 获取元素个数
 @return 个数
 */
-(int)eleCount {
    
    int eleCount = (self.rear - self.front + self.capacity) % self.capacity;
    NSLog(@"队列元素个数 = %d", eleCount);
    return eleCount;
}

@end

三、结果

测试

-(void)test_DataStructure_ArrayQueue {
    
    /// 构造循环队列
    ArrayQueue *arrayQueue = [ArrayQueue constrcutArrayQueueWithCapacity:5];
    
    /// enter Queue 入队列
    [arrayQueue enQueueWithElement:@(10)];
    [arrayQueue enQueueWithElement:@(30)];
    [arrayQueue enQueueWithElement:@(50)];
    [arrayQueue enQueueWithElement:@(80)];
    [arrayQueue enQueueWithElement:@(100)];
    
    /// 全部入队后 get eleCount 元素个数
    [arrayQueue eleCount];
    
    /// deque Queue 出队列
    [arrayQueue deQueueElement];
    [arrayQueue deQueueElement];
    [arrayQueue deQueueElement];
    [arrayQueue deQueueElement];
    [arrayQueue deQueueElement];
    
    /// 全部出队后  get eleCount 元素个数
    [arrayQueue eleCount];
    
}

打印

2019-10-19 15:20:57.323138+0800 运行时[76006:2342668] 入队列的元素 = 10, front = 0 , rear = 1
2019-10-19 15:20:57.323314+0800 运行时[76006:2342668] 入队列的元素 = 30, front = 0 , rear = 2
2019-10-19 15:20:57.323435+0800 运行时[76006:2342668] 入队列的元素 = 50, front = 0 , rear = 3
2019-10-19 15:20:57.323544+0800 运行时[76006:2342668] 入队列的元素 = 80, front = 0 , rear = 4
2019-10-19 15:20:57.323639+0800 运行时[76006:2342668] 队列已满，元素100不能被入列, front = 0 , rear = 4
2019-10-19 15:20:57.323721+0800 运行时[76006:2342668] 队列元素个数 = 4
2019-10-19 15:20:57.323844+0800 运行时[76006:2342668] 出队列的元素 = 10, front = 1 , rear = 4
2019-10-19 15:20:57.323945+0800 运行时[76006:2342668] 出队列的元素 = 30, front = 2 , rear = 4
2019-10-19 15:20:57.324033+0800 运行时[76006:2342668] 出队列的元素 = 50, front = 3 , rear = 4
2019-10-19 15:20:57.324140+0800 运行时[76006:2342668] 出队列的元素 = 80, front = 4 , rear = 4
2019-10-19 15:20:57.324245+0800 运行时[76006:2342668] 队列已空, front = 4 , rear = 4
2019-10-19 15:20:57.324344+0800 运行时[76006:2342668] 队列元素个数 = 0