Max Chunks To Make Sorted

MediumGreedygreedy

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.

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Problem

You are given an array arr that is a permutation of the integers 0 to n - 1. Cut arr into contiguous, non-empty **chunks**, sort each chunk on its own, and concatenate the chunks back in their original order. Return the **maximum** number of chunks for which the result equals the fully sorted array [0, 1, ..., n - 1]. Aim for O(n) time.

Examples

Input: arr = [4,3,2,1,0]
Output: 1
Any cut leaves a small value such as 0 in a later chunk than a larger value, so only the whole array works.
Input: arr = [1,0,2,3,4]
Output: 4
Chunks [1,0], [2], [3], [4] each sort into place.

Constraints

  • 1 <= n == arr.length <= 10
  • 0 <= arr[i] < n
  • All elements of arr are distinct

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.

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