[Python3] enumerate all candidates
Intuition\nLoop through nums as x and check if x can be the outlier. \n If x is eligible to be an outlier, then the remaining array sums to an even number, say 
**Intuition**\nLoop through `nums` as `x` and check if `x` can be the outlier. \n* If `x` is eligible to be an outlier, then the remaining array sums to an even number, say `cand`. And `cand/2` appears in `nums` (and cannot be `x`). \n\nFind the max of such `x`. \n\n**Analysis**\nTime complexity `O(N)`\nSpace complexity `O(N)`\n\n**Implementation**\n```\nclass Solution:\n    def getLargestOutlier(self, nums: List[int]) -> int:\n        freq = Counter(nums)\n        total = sum(nums)\n        ans = -inf \n        for i, x in enumerate(nums): \n            cand = total - x\n            if not cand & 1: \n                cand //= 2\n                if cand in freq and (x != cand or freq[cand] > 1): ans = max(ans, x)\n        return ans \n```
['Python3']