2026.9.17

75 颜色分类

class Solution:
    def sortColors(self, nums: list[int]) -> None:
        p0=p1=0
        for i,x in enumerate(nums):
            nums[i]=2
            if x<=1:
                nums[p1]=1
                p1+=1
            if x==0:
                nums[p0]=0
                p0+=1

31 下一个排列

class Solution:
    def nextPermutation(self, nums: list[int]) -> None:
        n=len(nums)
        i=n-2
        while nums[i]>=nums[i+1] and i>=0:
            i-=1
        if i>=0:
            j=n-1
            while nums[j]<=nums[i]:
                j-=1
            nums[i],nums[j]=nums[j],nums[i]
        left=i+1
        right=n-1
        while left<right:
            nums[left],nums[right]=nums[right],nums[left]
            left+=1
            right-=1

287 寻找重复数

class Solution:
    def findDuplicate(self, nums: list[int]) -> int:
        slow=fast=0
        while True:
            slow=nums[slow]
            fast=nums[nums[fast]]
            if slow==fast:break
        head=0
        while head!=slow:
            head=nums[head]
            slow=nums[slow]
        return head