python构建堆
- # 构建树实现堆
- class BinHeap:
- def __init__(self):
- self.heapList = [0]
- self.currentSize = 0
-
- #插入新结点后必要时交换子节点和父节点的位置保持堆的性质
- def percUp(self, i):
- while i//2 > 0:
- if self.heapList[i] < self.heapList[i//2]:
- temp = self.heapList[i//2]
- self.heapList[i//2] = self.heapList[i]
- self.heapList[i] = temp
- i = i//2
-
- # 插入节点
- def insert(self, k):
- self.heapList.append(k)
- self.currentSize += 1
- self.percUp(self.currentSize)
-
- # 删除堆顶元素后, 交换堆尾和空堆顶的位置并实现元素的下沉
- def percDown(self, i):
- while (i*2) <= self.currentSize:
- mc = self.minChild(i)
- if self.heapList[i] > self.heapList[mc]:
- temp = self.heapList[i]
- self.heapList[i] = self.heapList[mc]
- self.heapList[mc] = temp
- i = mc
-
- def minChild(self, i):
- if i * 2 + 1 > self.currentSize:
- return i * 2
- else:
- if self.heapList[i*2] < self.heapList[i*2+1]:
- return i * 2
- else:
- return i * 2 + 1
-
- def delMin(self):
- retval = self.heapList[1]
- self.heapList[1] = self.heapList[self.currentSize]
- self.currentSize = self.currentSize - 1
- self.heapList.pop()
- self.percDown(1)
- return retval
-
- def buildHeap(self, alist):
- i = len(alist) // 2
- self.currentSize = len(alist)
- self.heapList = [0] + alist[:]
- while (i > 0):
- self.percDown(i)
- i = i - 1
- return self.heapList
-
- H = BinHeap()
- print(H.buildHeap([9, 6, 5, 2, 3]))
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