快速排序

快速排序python代码：

def partPos( arr , left , right ):
    #选取中间的mid为分隔数值
    mid = (left+right)//2
    #将其与arr[right]交换
    arr[mid],arr[right] = arr[right],arr[mid]
    pivot = arr[right]
    i = left
    for j in range(left,right+1):
        if arr[j]<=pivot:
            arr[i],arr[j] = arr[j],arr[i]
            i += 1
    return i-1

def quickSort( arr , left , right ):
    if left<right:
        #获取此次分隔后中间数值位置
        pos = partPos( arr , left , right )
        #新一轮分隔
        quickSort( arr , left , pos-1 )
        quickSort( arr , pos+1 , right )
    return

nums = [9,8,7,6,5,4,3,2,1]
quickSort(nums,0,8)
print(nums)

输出：[1, 2, 3, 4, 5, 6, 7, 8, 9]