Longest Turbulent Subarray

MediumSliding Windowsliding window

Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.

Practice this as a mock interviewFree to start, no account needed

Problem

A contiguous subarray is **turbulent** when the comparison between neighbouring elements flips direction at every step, as in a < b > c < d or a > b < c > d. Any subarray of length 1 is turbulent. A length-2 subarray is turbulent only when its two elements differ. Given an integer array arr, return the length of its longest turbulent subarray.

Examples

Input: arr = [9,4,2,10,7,8,8,1,9]
Output: 5
[4,2,10,7,8] goes 4 > 2 < 10 > 7 < 8.
Input: arr = [4,8,12,16]
Output: 2
The values only increase, so the best turbulent runs have length 2.
Input: arr = [100]
Output: 1
A single element is turbulent.

Constraints

  • 1 <= arr.length <= 4 * 10^4
  • 0 <= arr[i] <= 10^9

What the interviewer grades

A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.

More sliding window problems