参考代码：

class Solution:
    def longestCon(self, num):
        dict = {}
        for x in num:
            dict[x] = 1
        ans = 0
        for x in num:
            if x in dict:
                len = 1
                del dict[x]
                l = x - 1
                r = x + 1
                while l in dict:
                    del dict[l]
                    l -= 1
                    len -= 1
                while r in dict:
                    del dict[r]
                    r += 1
                    len += 1
                if ans < len:
                    ans = len
        return ans