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#!/usr/bin/env python
import typing
class Solution:
def maxLength(self, arr: typing.List[str]) -> int:
result = [0]
self.dfs(arr, "", 0, result)
return result[0]
def dfs(self, arr, path, idx, result):
if self.isUniqueChars(path):
result[0] = max(result[0], len(path))
if idx == len(arr) or not self.isUniqueChars(path):
return
for i in range(idx, len(arr)):
self.dfs(arr, path + arr[i], i + 1, result)
def isUniqueChars(self, s):
char_set = set()
for c in s:
if c in char_set:
return False
char_set.add(c)
return True
def main():
solution = Solution()
print(solution.maxLength(["un", "iq", "ue"]))
print(solution.maxLength(["cha", "r", "act", "ers"]))
print(solution.maxLength(["abcdefghijklmnopqrstuvwxyz"]))
if __name__ == "__main__":
main()
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