0067.add-binary

Given two binary strings a and b, return their sum as a binary string.

Example 1:

Input: a = "11", b = "1" Output: "100"

Example 2:

Input: a = "1010", b = "1011" Output: "10101"

Constraints:

1 <= a.length, b.length <= 104 a and b consist only of '0' or '1' characters. Each string does not contain leading zeros except for the zero itself.