# LeetCode--Longest Consecutive Sequence（最长连续序列） Python

Longest Consecutive Sequence（最长连续序列）

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

Your algorithm should run in O(n) complexity.

```class Solution(object):
def longestConsecutive(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
Dict = {}
for i in nums:
Dict[i] = 1
List = Dict.keys()
count_max = 0
while(len(Dict)):
List = Dict.keys()
count = 1
temp_left = List[0]
temp_right = List[0]
Dict.pop(temp_left)
while(1):
if temp_left-1 in Dict and temp_right+1 in Dict:
count = count+2
temp_left = temp_left-1
temp_right = temp_right+1
Dict.pop(temp_left)
Dict.pop(temp_right)
continue
elif temp_left-1 not in Dict and temp_right+1 in Dict:
count = count+1
temp_right = temp_right+1
Dict.pop(temp_right)
continue
elif temp_left-1 in Dict and temp_right+1 not in Dict:
count = count+1
temp_left = temp_left-1
Dict.pop(temp_left)
continue
else:
if count>count_max:
count_max=count
break
else:
break
return count_max```