0896._monotonic_array.md

896. Monotonic Array

难度: Easy

刷题内容

原题连接

• https://leetcode.com/problems/monotonic-array

内容描述

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

Exmaple 3:

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

Example 4:

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

Example 5:

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

解题方案

思路 1 - 时间复杂度: O(N)- 空间复杂度: O(1)******

遍历list, 如果不满足条件, flag设为False, 返回两者之一。

beats 54.15%

class Solution(object):
    def isMonotonic(self, A):
        """
        :type A: List[int]
        :rtype: bool
        """
        if not A or len(A) <= 1:
            return True
        
        increasing = decreasing = True

        for i in range(len(A) - 1):
            if A[i] > A[i+1]: 
                increasing = False
            if A[i] < A[i+1]: 
                decreasing = False
        
        return increasing or decreasing