✅ One Line Solution
(Disclaimer: this is not an example to follow in a real project - it is written for fun and training mostly)\n\n# Code #1\nTime complexity: O(n). Space complexi
(Disclaimer: this is not an example to follow in a real project - it is written for fun and training mostly)\n\n# Code #1\nTime complexity: $$O(n)$$. Space complexity: $$O(n)$$.\n```\nclass Solution:\n    def findMaxK(self, a: List[int]) -> int:\n        return max(filter(lambda v:-v in d,d:={*a}),default=-1)\n```\n\n# Code #2\nTime complexity: $$O(n*log(n))$$. Space complexity: $$O(n)$$.\n```\nclass Solution:\n    def findMaxK(self, a: List[int]) -> int:\n        return next((abs(v) for v,u in pairwise(sorted(a,key=abs)[::-1]) if v==-u),-1)\n```\n\n(Disclaimer 2: all code above is just a product of fantasy, it is not claimed to be pure impeccable oneliners - please, remind about drawbacks only if you know how to make it better. PEP 8 is violated intentionally)
['Array', 'Hash Table', 'Sorting', 'Python', 'Python3']