堆结构

class Solution:
    def maxheap(self,arr):
        length = len(arr)
        for i in range(len(arr)//2,-1,-1): #之所以从len(arr)//2开始是因为 len(arr)//2为最后一个非叶节点
            self.heaprify(arr,i,length)

    def heaprify(self,arr,i,length):
        left = 2*i+1
        right = 2*i+2
        largest = i
        if left<length and arr[left]>arr[largest]:
            largest = left
        if right<length and arr[right]>arr[largest]:
            largest = right
        if largest!=i:
            arr[largest],arr[i] = arr[i],arr[largest]
            self.heaprify(arr,largest,length)

    def heapSort(self,arr):
        self.maxheap(arr)
        length = len(arr)
        for i in range(len(arr)-1,-1,-1):
            arr[0],arr[i] = arr[i],arr[0]
            length-=1
            self.heaprify(arr,0,length)
        return arr