Longest Mountain in Array
CodingPhone ScreenSoftware EngineerReported Mar, 2026
Examples
Example 1:
Input: arr = [2,1,4,7,3,2,5]
Output: 5
Explanation:
Example 2:
Input: arr = [2,2,2]
Output: 0
Explanation:
Example 1:
Input: arr = [2,1,4,7,3,2,5]
Output: 5
Explanation:
Example 2:
Input: arr = [2,2,2]
Output: 0
Explanation:
You may recall that an array arr is a mountain array if and only if:
arr.length >= 3i with 0 < i < arr.length - 1 such that:
arr[0] < arr[1] < ... < arr[i - 1] < arr[i]arr[i] > arr[i + 1] > ... > arr[arr.length - 1]Given an integer array arr, return the length of the longest subarray, which is a mountain. Return 0 if there is no mountain subarray.
The largest mountain is [1,4,7,3,2] with length 5.
No mountain — there must be strictly increasing then strictly decreasing sides of length >= 1 each.
1 <= arr.length <= 10^40 <= arr[i] <= 10^4