JuniorArray
Valid Mountain Array
Given an array of integers arr, return true if and only if it is a valid mountain array.
Recall that arr is a mountain array if and only if:
arr.length >= 3- There exists some
iwith0 < i < arr.length - 1such that: arr[0] < arr[1] < ... < arr[i - 1] < arr[i]arr[i] > arr[i + 1] > ... > arr[arr.length - 1]
Example 1
# # # 2 1
Input
arr = [2,1]Output
falseThe array has fewer than three elements, so it cannot be a valid mountain array.
Example 2
# # # # # # # # # # # # # 3 5 5
Input
arr = [3,5,5]Output
falseThe array does not strictly increase before decreasing because two adjacent peak values are equal.
Constraints
- 1 <= arr.length <= 10^4
- 0 <= arr[i] <= 10^4