3105. Longest Strictly Increasing or Strictly Decreasing Subarray

Problem Link

Description

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You are given an array of integers nums. Return the length of the longest subarray of nums which is either strictly increasing or strictly decreasing.

 

Example 1:

Input: nums = [1,4,3,3,2]

Output: 2

Explanation:

The strictly increasing subarrays of nums are [1], [2], [3], [3], [4], and [1,4].

The strictly decreasing subarrays of nums are [1], [2], [3], [3], [4], [3,2], and [4,3].

Hence, we return 2.

Example 2:

Input: nums = [3,3,3,3]

Output: 1

Explanation:

The strictly increasing subarrays of nums are [3], [3], [3], and [3].

The strictly decreasing subarrays of nums are [3], [3], [3], and [3].

Hence, we return 1.

Example 3:

Input: nums = [3,2,1]

Output: 3

Explanation:

The strictly increasing subarrays of nums are [3], [2], and [1].

The strictly decreasing subarrays of nums are [3], [2], [1], [3,2], [2,1], and [3,2,1].

Hence, we return 3.

 

Constraints:

• 1 <= nums.length <= 50
• 1 <= nums[i] <= 50

Solution

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Python3

class Solution:
    def longestMonotonicSubarray(self, nums: List[int]) -> int:
        N = len(nums)
        res = inc = dec = 1
        
        for i in range(1, N):
            if nums[i] > nums[i - 1]:
                inc += 1
                res = max(res, inc)
            else:
                inc = 1
            
            if nums[i] < nums[i - 1]:
                dec += 1
                res = max(res, dec)
            else:
                dec = 1
                
        return res