描述：

Given an unsorted array of integers, find the length of the longest consecutive elements sequence.

例子：

Given [100, 4, 200, 1, 3, 2],
The longest consecutive elements sequence is [1, 2, 3, 4]. Return its length: 4.

要求：

Your algorithm should run in O(n) complexity.

分析

从未排序的数组中寻找最长的连续的数字，必然要循环一遍所有的数字，因为连续，所以以pop出来的数字为基准，向左右扩散，直到没有连续的，利用了pop和in的特性。 

代码：

class Solution:
    def longestConsecutive(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        final_length=0
        num_dict=dict()
        maxlen_cur=0
        while nums:
            m=n=nums.pop()
            maxlen_cur=1
            while m-1 in nums:
                nums.remove(m-1)
                maxlen_cur+=1
                # m-=1
                m-=1
            while n+1 in nums:
                nums.remove(n+1)
                maxlen_cur+=1
                n+=1
            final_length=max(maxlen_cur,final_length)
        return final_length

if __name__=='__main__':
    a=[100, 4, 200, 1, 3, 2]
    st=Solution()
    out=st.longestConsecutive(a)
    print(out)