"""
525. Contiguous Array
Difficulty: Medium
https://leetcode.com/problems/contiguous-array/

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Given a binary array nums, return the maximum length of a contiguous
subarray with an equal number of 0 and 1.



Example 1:

Input: nums = [0,1]
Output: 2
Explanation: [0, 1] is the longest contiguous subarray with an equal
number of 0 and 1.

Example 2:

Input: nums = [0,1,0]
Output: 2
Explanation: [0, 1] (or [1, 0]) is a longest contiguous subarray with
equal number of 0 and 1.

Example 3:

Input: nums = [0,1,1,1,1,1,0,0,0]
Output: 6
Explanation: [1,1,1,0,0,0] is the longest contiguous subarray with
equal number of 0 and 1.



Constraints:

        • 1 <= nums.length <= 10^5

        • nums[i] is either 0 or 1.
"""


class Solution:
    def findMaxLength(self, nums: List[int]) -> int:
        map = {0: -1}
        count = 0
        longest = 0

        for i, num in enumerate(nums):
            count += 1 if num == 1 else -1

            if count in map:
                longest = max(longest, i - map[count])
            else:
                map[count] = i

        return longest