Permutation Sequence

class Solution:    def nextPermutation(self, nums: List[int]) -> None:        n = len(nums)        i = n - 1        while i > 0:            if nums[i - 1] < nums[i]:                break            i -= 1        if i == 0:            nums.reverse()            return        mdiff = float('inf')        closest = None        for j in range(i, n):            if nums[j] > nums[i - 1] and nums[j] - nums[i - 1] <= mdiff:                mdiff = nums[j] - nums[i - 1]                closest = j        if closest:            nums[i - 1], nums[closest] = nums[closest], nums[i - 1]        for j in range(i, (i + n) // 2):            nums[j], nums[n - j + i - 1] = nums[n - j + i - 1], nums[j]    def getPermutation(self, n: int, k: int) -> str:        nums = list(range(1, n + 1))        for _ in range(k - 1):            self.nextPermutation(nums)        return "".join(map(str, nums))