下一个排列

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param nums int整型一维数组 
# @return int整型一维数组
#
class Solution:
    def nextPermutation(self , nums: List[int]) -> List[int]:
        # write code here
        # 判断是否为下降序列
        is_decrese = True
        for i in range(1, len(nums)):
            if nums[i] > nums[i-1]:
                is_decrese = False
        if is_decrese:
            return nums[::-1]

        # 右指针最右边，逐步往左边找比右指针小的值，找到交换返回即可
        # 一次次找，找不到就左移右指针
        right = len(nums)-1
        while right > 0:
            for i in range(right-1, -1,-1):
                if nums[i] < nums[right]:
                    nums[i], nums[right] = nums[right], nums[i]
                    return nums
            right -= 1

        return nums

class Solution:
    def nextPermutation(self , nums: List[int]) -> List[int]:
        # write code here
        if len(nums) < 2 :
            return nums
        p1 = 0
        p2 = len(nums) - 2
        
        flag = 0
        while p2 >= 0:
            for i in range(p2, len(nums)):
                if nums[i] > nums[p2]:
                    tmp = nums[i]
                    nums[i] = nums[p2]
                    nums[p2] = tmp
                    flag = 1
                    break
            if flag == 1:
                break
            else:
                p2 -= 1
        if flag == 0:
            nums.sort()
        
        return nums