LeetCode - Add Binary

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

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

For example,

a =

"11"

b =

"1"

Return

"100"

.
这道题就跟所有加法题一样，只要注意进位，和一个数加完后，处理另一个数剩余的位就行。
代码如下：

public String addBinary(String a, String b) {
char[] sa = a.toCharArray();
char[] sb = b.toCharArray();

int i=sa.length-1;
int j = sb.length-1;
char[] longer = i>=j? sa:sb;
int left = i>=j? i:j;
int carry = 0;
while(i>=0 && j>=0){
int val = (sa[i]-'0') + (sb[j]-'0') + carry;
longer[left] = (char)(val%2 + '0');
carry = val/2;
i--;
j--;
left--;
}

while(left>=0){
int val = (longer[left]-'0') + carry;
longer[left] = (char)(val%2 + '0');
carry = val/2;
left--;
}
String rst = new String(longer);
if(carry>0) rst = "1" + rst;
return rst;
}