堆实现优先级队列（算法导论第六章）

最新推荐文章于 2024-09-10 11:06:15 发布

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本文介绍了一个最大堆的数据结构实现，包括获取最大元素、提取最大元素、增加键值以及插入新元素等关键操作，并提供了相应的C++代码实现。

与前一篇堆的实现相关。

此页代码未经调试！

//priority queue

int HeapMaximum( int *heap, int heapSize )
{
	return heap[heapSize - 1];
}

int HeapExtractMax( int *heap, int heapSize )
{
	if ( heapSize < 1 )
	{
		cout << "heap underflow!" << endl;
		return -1;
	}
	int max = heap[0];
	heap[0] = heap[heapSize - 1];
	--heapSize;
	MaxHeapify( heap, 0, heapSize );
	return max;
}

int HeapIncreaseKey( int *heap, int index, int key, int heapSize )
{
	if ( key < heap[index] )
	{
		cout << "The new key is smaller than current key!";
		return -1;
	}
	heap[index] = key;
	int parent = (index - 1) / 2;
	if ( heap[index] <= heap[parent] )
	{
		return 0;
	}
	else
	{
		while ( index > 0 && heap[index] > heap[parent] )
		{
			int temp = heap[parent];
			heap[parent] = heap[index];
			heap[index] = temp;
			index = parent;
			parent = (index - 1) / 2;
		}
	}
	return 0;
}

int* MaxHeapInsert( int *heap, int key, int heapSize )
{
	int *newHeap = new int[heapSize + 1];
	for ( int i = 0; i < heapSize; ++i )
	{
		newHeap[i] = heap[i];
	}
	delete [] heap;
	newHeap[heapSize] = INT_MIN;
	++heapSize;
	HeapIncreaseKey( newHeap, heapSize - 1, key, heapSize );
	return newHeap;
}