Contiguous Array

MediumArrays & Hashingprefix sum

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

Given a binary array nums, return the length of the longest contiguous subarray that contains an equal number of 0s and 1s. Return 0 if no such subarray exists. Aim for O(n) time.

Examples

Input: nums = [0,1]
Output: 2
The whole array has one 0 and one 1.
Input: nums = [0,1,0]
Output: 2
Either [0, 1] or [1, 0] works.
Input: nums = [0,0,1,0,0,0,1,1]
Output: 6
nums[2..7] = [1, 0, 0, 0, 1, 1] has three of each.

Constraints

  • 1 <= nums.length <= 10^5
  • `nums[i]` is either 0 or 1

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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