用objective c 生成循环队列

下面是一个使用 Objective-C 实现的循环队列示例代码：

@interface CircularQueue : NSObject

- (instancetype)initWithCapacity:(NSUInteger)capacity;

- (BOOL)isEmpty;
- (BOOL)isFull;
- (NSUInteger)size;
- (void)enqueue:(id)object;
- (id)dequeue;
- (id)front;
- (id)rear;

@end


@implementation CircularQueue {
    NSUInteger _capacity;
    NSUInteger _head;
    NSUInteger _tail;
    NSMutableArray *_data;
}

- (instancetype)initWithCapacity:(NSUInteger)capacity {
    self = [super init];
    if (self) {
        _capacity = capacity;
        _head = 0;
        _tail = 0;
        _data = [NSMutableArray arrayWithCapacity:capacity];
    }
    return self;
}

- (BOOL)isEmpty {
    return _head == _tail;
}

- (BOOL)isFull {
    return (_tail + 1) % _capacity == _head;
}

- (NSUInteger)size {
    return (_tail - _head + _capacity) % _capacity;
}

- (void)enqueue:(id)object {
    if ([self isFull]) {
        NSLog(@"Queue is full");
        return;
    }
    [_data addObject:object];
    _tail = (_tail + 1) % _capacity;
}

- (id)dequeue {
    if ([self isEmpty]) {
        NSLog(@"Queue is empty");
        return nil;
    }
    id object = [_data objectAtIndex:_head];
    [_data removeObjectAtIndex:_head];
    _tail = (_tail - 1 + _capacity) % _capacity;
    return object;
}

- (id)front {
    if ([self isEmpty]) {
        NSLog(@"Queue is empty");
        return nil;
    }
    return [_data objectAtIndex:_head];
}

- (id)rear {
    if ([self isEmpty]) {
        NSLog(@"Queue is empty");
        return nil;
    }
    return [_data objectAtIndex:_tail - 1];
}

@end

使用示例：

CircularQueue *queue = [[CircularQueue alloc] initWithCapacity:5];
[queue enqueue:@1];
[queue enqueue:@2];
[queue enqueue:@3];
NSLog(@"%@", [queue front]); // Output: 1
NSLog(@"%@", [queue rear]); // Output: 3
[queue dequeue];
NSLog(@"%@", [queue front]); // Output: 2
NSLog(@"%@", [queue rear]); // Output: 3