Ask a question about subset and permute in Python

Example 1:

Input: ‘XXY’
Output: 8

Analysis: you can make ‘X’, ‘Y’, ‘XY’, ‘YX’, ‘XX’, ‘XXY’, ‘XYX’, ‘YXX’ 

<pre>class Solution:
    def Q1(self, s: str) -> int:
        def subsetsWithDup(nums):
            nums.sort()
            result = []

            def subset(S, sub):
                result.append(sub)

                for i in range(len(S)):
                    if i > 0 and S[i] == S[i - 1]:
                        continue

                    subset(S[i + 1:], sub + [S[i]])

            subset(nums, [])
            return result

        def permute(nums):
            if len(nums) == 0:
                return []

            if len(nums) == 1:
                return [nums]

            result = []

            for i in range(len(nums)):
                m = nums[i]
                sublst = nums[:i] + nums[i + 1:]

                for p in permute(sublst):
                    result.append([m] + p)

            return result

        nums = list(s)
        subsets = subsetsWithDup(nums)
        result_set = set()

        for subset in subsets:
            perms = permute(subset)
            for perm in perms:
                result_set.add(''.join(perm))

        return len(list(result_set))