(java)Add Binary

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

For example,

a =

"11"

b =

"1"

Return

"100"

.

思路:就是普通的加法，加入进位就行。注意循环结束的时候，如果进位为1，则在前面加一个1就可

代码如下(已通过leetcode)

public class Solution {

public String addBinary(String a, String b) {

int lengthA=a.length();

int lengthB=b.length();

if(a.length()>b.length()) {

for(int i=0;i<lengthA-lengthB;i++) b='0'+b;

} else for(int i=0;i<lengthB-lengthA;i++) a='0'+a;

int temp=0;

String ans="";

for(int i=a.length()-1;i>=0;i--) {

if((a.charAt(i)-'0')+(b.charAt(i)-'0')+temp>1) {

ans=(a.charAt(i)-'0')+(b.charAt(i)-'0')+temp-2+ans;

temp=1;

} else {

ans=(a.charAt(i)-'0')+(b.charAt(i)-'0')+temp+ans;

temp=0;

}

}

if(temp==1) ans=temp+ans;

return ans;

}

}