Add Binary

Add Binary

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

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

class Solution {
public:
    string addBinary(string a, string b) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int length1=a.size();
        int length2=b.size();
        if(length2<length1){//keep b is longer
            string temp=a;
            a=b;
            b=temp;
            int c=length1;
            length1=length2;
            length2=c;
        }
        a.insert(0,length2-length1,'0');
        char buffer[]={'0','1'};
        int jin,yu;
        jin=0;yu=0;
        for(int i=length2-1 ; i>=0 ; i--){
            yu=((a[i]-'0')+(b[i]-'0')+jin)%2;
            jin=((a[i]-'0')+(b[i]-'0')+jin)/2;
            b[i]=buffer[yu];
        }
        if(jin)
            b.insert(0,1,'1');
        return b;        
    }
};

啥也不说了，这题太简单了……很快就通过了