Description
Given an array of integers arr, return true if and only if it is a valid mountain array with strictly increasing then strictly decreasing elements.
Examples
Input:
arr = [0,3,2,1]Output:
trueExplanation:
Peak at index 1.
Input:
arr = [0, 3, 2, 1]Output:
trueExplanation:
Peak at index 1 with strictly increasing [0,3] and strictly decreasing [3,2,1].
Input:
arr = [1,2,3,2]Output:
trueExplanation:
Peak at index 2 with strictly increasing [1,2,3] and strictly decreasing [3,2].
Constraints
- •
1 ≤ arr.length ≤ 10^4