896. Monotonic Array-单调数列

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

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

Return true if and only if the given array A is monotonic.

Example 1:
Input: [1,2,2,3]
Output: true

Example 2:
Input: [6,5,4,4]
Output: true

Example 3:
Input: [1,3,2]
Output: false

Example 4:
Input: [1,2,4,5]
Output: true

Example 5:
Input: [1,1,1]
Output: true

Note:

• 1 <= A.length <= 50000
• -100000 <= A[i] <= 100000

Solution in python:

class Solution:
    def isMonotonic(self, A: List[int]) -> bool:
        if len(A) <= 1:
            return True
        else:
            if A[-1] >= A[0]:
                for i in range(len(A)-1):
                    if A[i+1] < A[i]:
                        return False
            else:
                for i in range(len(A)-1):
                    if A[i+1] > A[i]:
                        return False
            return True