class Solution:
    def findMaxLength(self, nums):
        # Map to store (prefix_sum: first_index_it_occurred)
        # Initialize with 0: -1 to handle subarrays starting from index 0
        indices = {0: -1}
        max_len = 0
        count = 0
        
        for i, num in enumerate(nums):
            # Treat 0 as -1 and 1 as 1
            count += 1 if num == 1 else -1
            
            if count in indices:
                # Calculate length: current index - first occurrence of this sum
                max_len = max(max_len, i - indices[count])
            else:
                # Only store the first occurrence to maximize the distance/length
                indices[count] = i
                
        return max_len