Is there a heap in python?

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Release: 2019-08-01 10:10:39
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Heap (English: heap) is the collective name for a special type of data structure in computer science;

Is there a heap in python?

The definition of heap: a sequence of n elements { k1,k2,ki,…,kn} If and only if the following relationship is satisfied, it is called a heap. (Recommended learning: Python video tutorial)

"ki<=k2i,ki<=k2i+1;或ki>=k2i,ki>=k2i+1.(i=1,2,…,[n/2])"
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This is the standard heap definition, but there is no independent heap type in python, it is just a module that contains some heap operation functions (heapq = the first letter of heap queue), in fact, the heap is a special list in python;

Briefly introduce the methods in heapq

import heapq
1.heapq.heappush(heap,item)  #heap为定义堆,item 增加的元素;
eg.
  heap=[]
  heapq.heappush(heap, 2)
2.heapq.heapify(list)        #将列表转换为堆
eg.
   list=[5,8,0,3,6,7,9,1,4,2]
   heapq.heapify(list) 
3.heapq.heappop(heap)        #删除最小的值
eg.
  heap=[2, 4, 3, 5, 7, 8, 9, 6]
  heapq.heappop(heap) ---->heap=[3, 4, 5, 7, 9, 6, 8]
4.heapq.heapreplace(heap, item)     #删除最小元素值,添加新的元素值
eg.
  heap=[2, 4, 3, 5, 7, 8, 9, 6]
  heapq.heapreplace(heap, 11) ------>heap=[2, 3, 4, 6, 8, 5, 7, 9, 11]
5.heapq.heappushpop(heap, item)     #首判断添加元素值与堆的第一个元素值对比,如果大于则删除最小元素,然后添加新的元素值,否则不更改堆
eg.
   条件:item >heap[0]
   heap=[2, 4, 3, 5, 7, 8, 9, 6]
   heapq.heappushpop(heap, 9)---->heap=[3, 4, 5, 6, 8, 9, 9, 7]
   条件:item
   heap=[2, 4, 3, 5, 7, 8, 9, 6]
   heapq.heappushpop(heap, 9)---->heap=[2, 4, 3, 5, 7, 8, 9, 6]
6.heapq.merge(...)             #将多个堆合并
7.heapq.nlargest (n, heap)     #查询堆中的最大元素,n表示查询元素个数
eg.
  heap=[2, 3, 5, 6, 4, 8, 7, 9]
  heapq.nlargest (1, heap)--->[9]
8.heapq.nsmallest(n, heap)     #查询堆中的最小元素,n表示查询元素个数
eg.
 heap=[2, 3, 5, 6, 4, 8, 7, 9]
 heapq.nlargest (1, heap)--->[2]
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