Contiguous Array

class Solution {
public:
    int findMaxLength(vector<int>& nums) {
		vector<int> arr(2*nums.size() + 1, INT_MIN);
		arr[nums.size()] = -1;
        int maxLen = 0, sum = 0;
        for (int i = 0; i < nums.size(); i++) {
            sum += (nums[i] == 0 ? -1 : 1);
			if (arr[sum + nums.size()] >= -1)  maxLen = max(maxLen, i - arr[sum + nums.size()]);
			else  arr[sum + nums.size()] = i; 
        }
        return maxLen;
    }
};