在 python 堆中偷看
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Peeking in a heap in python
提问by Thomas
What is the official way of peeking in a python heap as created by the heapq libs? Right now I have
查看由 heapq 库创建的 python 堆的官方方法是什么？现在我有
def heappeak(heap):
smallest = heappop(heap)
heappush(heap, smallest)
return smallest
which is arguably, not very nice. Can I always assume that heap[0]is the top of the heap and use that? Or would that assume too much of the underlying implementation?
这可以说不是很好。我可以总是假设这heap[0]是堆的顶部并使用它吗？或者这是否会假设太多的底层实现？
回答by Stephan202
Yes, you can make this assumption, because it is stated in the documentation:
是的，您可以做出这个假设，因为它在文档中说明：
Heaps are arrays for which
heap[k] <= heap[2*k+1]andheap[k] <= heap[2*k+2]for all k, counting elements from zero. For the sake of comparison, non-existing elements are considered to be infinite. The interesting property of a heap is thatheap[0]is always its smallest element.
堆是数组，其中
heap[k] <= heap[2*k+1]和heap[k] <= heap[2*k+2]所有k，从零开始计数元素。为了比较，不存在的元素被认为是无限的。堆的有趣特性是它heap[0]总是最小的元素。
(And that's probably the reason there is no peekfunction: there is no need for it.)
（这可能就是没有peek函数的原因：不需要它。）
回答by DannyTree
If you're using Python 2.4 or newer, you can also use heapq.nsmallest().
如果您使用 Python 2.4 或更新版本，您还可以使用 heapq.nsmallest()。
