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Contiguous Array

Problem Statement​

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

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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.

Code​

class Solution:
    def findMaxLength(self, nums: List[int]) -> int:
        max_length =0
        hash={}
        count=0
        for i in range(len(nums)):
            current=nums[i]
            if current==0:
                count-=1 # decrement our count if our current element is 0
            else:
                # increment our count if current element is 1
             count+=1

            if count==0:
                # if count is 0, we have a new subarray with length+1
                max_length=i+1
            if count in hash:
                max_length=max(max_length,i-hash[count])
            else:
                hash[count]=i
        return max_length