An array is said to be monotonic in nature if it is either continuously increasing or continuously decreasing. Mathematically, An array A is continuously 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].

Sample Input:

[ 5, 7, 7, 8, 10, 20]

Sample Output:

True

数据结构和算法：初级练习题 #54 – 单调数组

给定一个数组，判断它是否单调。单调数组是指这个数组的数字要么是递增的，要么是递减的，不存在一会儿递增一会儿递减的情况，即不会有山峰存在，注意相邻的数字可以相同。

输入样例：

[ 5, 7, 7, 8, 10, 20]

输出样例：

True

Python Solution