Add Binary - Leetcode

public class Solution {
public String addBinary(String a, String b) {
StringBuilder sb = new StringBuilder();
int plus = 0; int ca,cb;
int i=a.length()-1,j=b.length()-1;
while(i>=0&&j>=0){
ca = a.charAt(i--)-'0';
cb = b.charAt(j--)-'0';
sb.append((ca+cb+plus)%2);
plus = (ca+cb+plus)/2;
}
while(i>=0){
ca = a.charAt(i--)-'0';
sb.append((ca+plus)%2);
plus = (ca+plus)/2;
}
while(j>=0){
cb = b.charAt(j--)-'0';
sb.append((cb+plus)%2);
plus = (cb+plus)/2;
}
if(plus > 0)
sb.append(plus%2);

sb.reverse();
return sb.toString();
}
}

思路： 就是实现二进制的加法器。

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

For example,

a =

"11"

b =

"1"

Return

"100"

.