排序算法：sort color

快排：

s= [6,7,5,4,3,2]
def quicksort(l,r):
    i,j = l,r
    global s
    x= s[l]
    if(l<r):
        while(i<j):
            while(i<j and s[j]>=x):
                j -= 1
            if(i<j):
                s[i] = s[j]
                i += 1
            while (i<j and s[i]<x):
                i += 1
            if(i<j):
                s[j] = s[i]
                j -= 1
        s[i] = x
        quicksort(l,i-1)
        quicksort(i+1,r)
quicksort(0,5)
print(s)

思想：

快速排序 | 菜鸟教程 (runoob.com)

class Solution:
    def sortColors(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        self.nums = nums
        self.quicksort(0,len(nums)-1)

    def quicksort(self,l,r):
        i ,j = l,r
        x = self.nums[l]
        if(l<r):
            while i<j:
                while (i<j) and x <= self.nums[j]:
                    j -= 1
                if (i<j):
                    self.nums[i] = self.nums[j]
                    i += 1
                while i<j and self.nums[i] < x:
                    i += 1
                if (i<j):
                    self.nums[j] = self.nums[i]
                    j -= 1
            self.nums[i] = x
            self.quicksort(l,i-1)
            self.quicksort(i+1,r)