# Program to find length of longest consecutive sequence in Python

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Suppose we have an unsorted array of numbers, we have to find the length of the longest sequence of consecutive elements.

So, if the input is like nums = [70, 7, 50, 4, 6, 5], then the output will be 4, as the longest sequence of consecutive elements is [4, 5, 6, 7]. so we return its length: 4.

To solve this, we will follow these steps −

• nums := all unique elements of nums

• max_cnt := 0

• for each num in nums, do

• if num - 1 not in nums, then

• cnt := 0

• while num is present in nums, do

• num := num + 1

• cnt := cnt + 1

• max_cnt := maximum of max_cnt and cnt

• return max_cnt

Let us see the following implementation to get better understanding −

## Example

Live Demo

class Solution:
def solve(self, nums):
nums = set(nums)
max_cnt = 0
for num in nums:
if num - 1 not in nums:
cnt = 0
while num in nums:
num += 1
cnt += 1
max_cnt = max(max_cnt, cnt)
return max_cnt
ob = Solution()
nums = [70, 7, 50, 4, 6, 5]
print(ob.solve(nums))

## Input

[70, 7, 50, 4, 6, 5]

## Output

4