Description
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
Python3
class Solution:
def isMonotonic(self, nums: List[int]) -> bool:
N = len(nums)
isIncreasing = None
for i in range(1, N):
if nums[i] == nums[i - 1]:
continue
elif nums[i] > nums[i - 1]:
if isIncreasing is None:
isIncreasing = True
elif not isIncreasing:
return False
else:
if isIncreasing is None:
isIncreasing = False
elif isIncreasing:
return False
return True