67. Add Binary (Easy)

https://leetcode.com/problems/add-binary/

Given two binary strings, return their sum (also a binary string).

The input strings are both non-empty and contains only characters 1 or 0.

Example 1:

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

Example 2:

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

Solutions

class Solution {

    public String addBinary(String a, String b) {
        String ans = "";

        int carrier = 0;

        int count = 0;
        while (count < a.length() || count < b.length()) {
            int x = 0;
            int y = 0;

            if (count < a.length()) {
                x = a.charAt(a.length() - count - 1) - '0';
            }

            if (count < b.length()) {
                y = b.charAt(b.length() - count - 1) - '0';
            }

            int sum = (x + y + carrier);

            ans = (sum % 2) + ans;

            carrier = sum / 2;

            count++;
        }

        if (carrier != 0) {
            ans = carrier + ans;
        }

        return ans;
    }
}

Incorrect Solutions

References