Contiguous Array
Module 12 · Prefix Sum
Problem
Given a binary array nums (only 0s and 1s), return the length of the
longest contiguous subarray with an equal number of 0s and 1s.
Examples
Example 1
Input
nums = [0,1]Output2Explanation. the whole array
Example 2
Input
nums = [0,1,0]Output2Explanation. [0,1] or [1,0]
Example 3
Input
nums = [0,0,1,0,1,1]Output6Explanation. the whole array: three 0s, three 1s
Constraints
1 ≤ n ≤ 10⁵.
Attempt it first
The reduction move: this doesn't look like a prefix-sum problem at first glance ("equal 0s and 1s" isn't obviously a sum), but a one-line transformation turns it into exactly Subarray Sum Equals K's shape. Find the transformation before opening the hint.