Monotonic Array

An array is monotonic if it is either monotone increasing or monotone decreasing.

An array nums is monotone increasing if for all i <= j, nums[i] <= nums[j]. An array nums is monotone decreasing if for all i <= j, nums[i] >= nums[j].

Given an integer array nums, return true if the given array is monotonic, or false otherwise.

Example 1:

Input: nums = [1,2,2,3]
Output: true

Example 2:

Input: nums = [6,5,4,4]
Output: true

Example 3:

Input: nums = [1,3,2]
Output: false

Constraints:

• 1 <= nums.length <= 105
• -105 <= nums[i] <= 105

SOLUTION:

class Solution:
    def isMonotonic(self, nums: List[int]) -> bool:
        n = len(nums)
        grctr = 0
        lsctr = 0
        for i in range(1, n):
            if nums[i] >= nums[i - 1]:
                grctr += 1
            if nums[i] <= nums[i - 1]:
                lsctr += 1
        return grctr == 0 or grctr == n - 1 or lsctr == 0 or lsctr == n - 1