Easy Python using set
The idea is to concatenate if all chars are unique within the concatenation. \n* To determine this we compare to the set of said concatenation. Last, keep a max
* The idea is to concatenate if all chars are unique within the concatenation. \n* To determine this we compare to the set of said concatenation. Last, keep a max variable to track the max.\n\n```\n    def maxLength(self, arr: List[str]) -> int:\n        maximum = 0\n        for index, string in enumerate(arr):\n            if len(string) == len(set(string)):\n                for index2, string2 in enumerate(arr):\n                    if index != index2:\n                        if len(string + string2) == len(set(string + string2)):\n                            string = string + string2 \n                    maximum = max(len(string), maximum)\n        return maximum\n```
['Python', 'Python3']