525. Contiguous Array

Medium

---

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.

Constraints:

• 1 <= nums.length <= 105

• nums[i] is either 0 or 1.

class Solution:
    def findMaxLength(self, nums: List[int]) -> int:
        d = {}
        count = 0
        result = 0
        for index in range(len(nums)):
            count += 1 if nums[index] == 1 else -1
            if count == 0:
                result = max(result, index+1)
            elif count in d:
                result = max(result, index - d[count])
            else:
                d[count] = index
        return result