tsanmmmm2000's Tech Blog

Question

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

For example,
a = "11"
b = "1"
Return "100".

My C# Solution

public class Solution {
    public string AddBinary(string a, string b) {
        var result = string.Empty;
        var aLength = a.Length;
        var bLength = b.Length;
        var carry = 0;
        while(aLength > 0 || bLength > 0)
        {
            var aBit = (aLength > 0) 
                ? Convert.ToInt32(a[aLength - 1].ToString()) 
                : 0;
            var bBit = (bLength > 0) 
                ? Convert.ToInt32(b[bLength - 1].ToString()) 
                : 0;
            
            var sum = aBit + bBit + carry;
            
            if (sum > 1)
            {
                result = (sum % 2) + result;
                carry = 1;
            }
            else
            {
                result = sum + result;
                carry = 0;
            }
            aLength--;
            bLength--;
        }
        return (carry == 1) ? carry + result : result;
    }
}