0031.py

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

    def reverse(self, nums: List[int], l, r) -> None:
        while l < r:
            nums[l], nums[r] = nums[r], nums[l]
            l += 1
            r -= 1