python, sort(), double pointers
https://leetcode.com/submissions/detail/854012683/\n\nRuntime: 126 ms, faster than 98.12% of Python3 online submissions for Largest Positive Integer That Exists
https://leetcode.com/submissions/detail/854012683/\n```\nRuntime: 126 ms, faster than 98.12% of Python3 online submissions for Largest Positive Integer That Exists With Its Negative.\nMemory Usage: 14.1 MB, less than 90.76% of Python3 online submissions for Largest Positive Integer That Exists With Its Negative.\n```\n```\nclass Solution:\n    def findMaxK(self, nums: List[int]) -> int:\n        nums.sort()\n        l = len(nums)\n        i, j = 0, l-1\n        while i<l and j>=0:\n            if -nums[i]==nums[j]:\n                return nums[j]\n            elif -nums[i]<nums[j]:\n                j-=1\n            else:\n                i+=1\n        return -1\n```
['Sorting', 'Python']