Given two binary strings A and B consisting of only 0s and 1s. Find the resultant string after adding the two Binary Strings.
Note: The input strings may contain leading zeros but the output string should not have any leading zeros.

Example 1:

Input:
A = "1101", B = "111"
Output: 10100
Explanation:
 1101
+ 111
10100

​Example 2:

Input: 
A = "10", B = "01"
Output: 11
Explanation: 
  10
+ 01
  11

User Task:
You don't need to read input or print anything. Your task is to complete the function addBinary() which takes 2 binary string A and B and returns a binary string denoting the addition of both the strings.

Expected Time Complexity: O(max(|A|, |B|)).
Expected Auxiliary Space: O(max(|A|, |B|)) (for output string).

Constraints:
1 <= |A|, |B| <= 1000000