改进参考代码：

1、迭代堆化

2、迭代的两种写法

def heapify(arr):
    n = len(arr)
    for i in reversed(range(n // 2)):
        shiftDown(arr,n,i)

def shiftDown(arr, n, k):
    while 2 * k + 1 < n:
        j = 2 * k + 1
        if j + 1 < n and arr[j + 1] < arr[j]:
            j += 1
        if arr[k] <= arr[j]:
            break
        arr[k], arr[j] = arr[j], arr[k]
        k = j

def shiftDown2(arr, n, k):
    smallest, l, r = k, 2 * k + 1, 2 * k + 2
    while l < n:
        if arr[l] < arr[smallest]:
            smallest = l
        if r < n and arr[r] < arr[smallest]:
            smallest = r
        if smallest == k:
            break
        else:
            arr[k], arr[smallest] = arr[smallest], arr[k]
            k = smallest
            l, r = 2 * k + 1, 2 * k + 2

def heapSort(arr):
    n=len(arr)
    heapify(arr)
    print("堆化：",arr)
    for i in range(n-1):
        arr[n-i-1],arr[0] = arr[0],arr[n-i-1]
        # print("交换最小值后：",arr)
        shiftDown(arr,n-i-1,0)
        # print("调整后：",arr)


arr = [3,2,1,9,7,8]
heapSort(arr)
print("排序后：",arr)