Form Array by Concatenating Subarrays of Another Array LeetCode solution in Python

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class Solution:
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    def canChoose(self, groups: List[List[int]], nums: List[int]) -> bool:
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        groups = ["-".join(str(s) for s in group) for group in groups]
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        nums = "-".join(str(s) for s in nums)
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        j = k = 0
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        while k < len(groups):
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            group = groups[k]
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            i = nums.find(group, j)
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            if i == -1:
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                return False
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            if i == 0 or i > 0 and nums[i - 1] == "-":
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                j = i + len(group)
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                k += 1
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            else:
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                j += 1
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        return True