Leetcode 896 .Monotonic Array
==
### Description
(easy)
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

### 想法
一開始直接頭尾相比就可以知道這是一格遞增或是遞減的數列，然後再用while把數列過一遍看看有沒有不符合的數，使用的時候記得index<numsize-1 不然我一開始有overflow會比不到最後一個，沒過回傳false有過回傳true
### 程式碼
#### python:

class Solution:
    def isMonotonic(self, nums: List[int]) -> bool:
        index=0
        if nums[0]>nums[-1]-1:
            while index<len(nums)-1:
                if nums[index]<nums[index+1]:   return False
                index+=1
        else:
            while index<len(nums)-1:
                if nums[index]>nums[index+1]:   return False
                index+=1
        return True

Runtime: 1036 ms
Memory Usage: 28.1 MB
faster than 92% of python3 users

bool isMonotonic(int* nums, int numsSize){
    int index=0;
    if(nums[0]>nums[numsSize-1]){
        while(index<numsSize-1){
            if(nums[index]<nums[index+1])
                return false;
            index++;
        }
    }else{
        while(index<numsSize-1){
            if(nums[index]>nums[index+1])
                return false;
            index++;
        }
    }
    return true;
}

Runtime: 185 ms
Memory Usage: 14 MB
faster than 75% c users