# 896. Monotonic Array

**<font color=red>难度: Easy</font>**

## 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%

```python
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
```
