67. Add Binary

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

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

 1 public class Solution {
 2     public String addBinary(String a, String b) {
 3     if (a == null || a == "")
 4         return b;
 5     if (b == null || b == "")
 6         return a;
 7     int carry = 0;
 8     String ret = "";
 9     int l1 = a.length()-1;
10     int l2 = b.length()-1;
11     while (l1 >= 0 || l2 >= 0 || carry == 1) {
12         if (l1 >= 0) {
13             carry += Integer.parseInt(a.charAt(l1)+"");
14             l1--;
15         }
16         if (l2 >= 0) {
17             carry += Integer.parseInt(b.charAt(l2)+"");
18             l2--;
19         }
20         ret = String.valueOf(carry%2) + ret;
21         carry /= 2;
22     }
23     return ret;
24 }
25 }

 

posted @ 2016-04-07 21:31  Loyal_1884  阅读(126)  评论(0)  编辑  收藏  举报