2024-01-23 07:54:38 +0000 UTC

class Solution:
    def maxLength(self, arr: List[str]) -> int:
        cur = set()
        length = len(arr)
        max_length = 0

        def backtrack(start: int) -> None:
            nonlocal max_length 
            
            for i in range(start, length):
                new_subs = arr[i]
                new = set(new_subs)
                if len(new_subs) != len(new) or len(cur.intersection(new)) != 0:
                    continue
                cur.update(new)
                backtrack(i + 1)
                cur.difference_update(new)

            max_length = max(max_length, len(cur))

        backtrack(0)

        return max_length