@interface LCPriorityQueue : NSObject


/// 创建一个优先级队列
+(instancetype)priorityQueue;


/// 创建一个优先级队列
/// @param comparator 自定义比较器
+(instancetype)priorityQueueWithComparator:(nullable LCCompareBlock)comparator;

/// 元素的数量
-(int)size;

/// 是否为空
-(BOOL)isEmpty;

/// 入队
-(void)enQueue:(nonnull id)element;

/// 出队
-(id)deQueue;

/// 获取队列的头元素
-(id)front;

/// 清空
-(void)clear;

@end

@interface LCPriorityQueue()
@property(nonatomic,strong)LCBinaryHeap * heap;
@property(nonatomic,copy)LCCompareBlock comparator;
@end

@implementation LCPriorityQueue

/// 创建一个优先级队列
+(instancetype)priorityQueue{
    return [self priorityQueueWithComparator:nil];
}


/// 创建一个优先级队列
/// @param comparator 自定义比较器
+(instancetype)priorityQueueWithComparator:(nullable LCCompareBlock)comparator{
    LCPriorityQueue * pQueue = [[LCPriorityQueue alloc] init];
    pQueue.comparator = comparator;
    return pQueue;
}


-(LCBinaryHeap *)heap{
    if(_heap == nil){
        _heap = [LCBinaryHeap binaryHeapWithComparator:self.comparator];
    }
    return _heap;
}


/// 元素的数量
-(int)size{
    return self.heap.size;
}

/// 是否为空
-(BOOL)isEmpty{
    return self.heap.isEmpty;
}

/// 入队
-(void)enQueue:(nonnull id)element{
    [self.heap add:element];
}

/// 出队
-(id)deQueue{
    return [self.heap remove];
}

/// 获取队列的头元素
-(id)front{
    return self.heap.get;
}

/// 清空
-(void)clear{
    [self.heap clear];
}


#pragma mark - 内部方法

/// 获取两个元素的比较结果
/// @param element1 元素1
/// @param element2 元素2
-(LCCompareType)_compareElement1:(nonnull id)element1 element2:(nonnull id)element2{
    assert(element1);
    assert(element2);
    return self.comparator?self.comparator(element1,element2):(LCCompareType)([element1 compare:element2]);
}