leetcode_c++：Add Binary（067）

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) {
    int alen = a.size();
    int blen = b.size();
    bool carry = false;
    string result;
    while( alen> || blen>) {
        int abit = alen<= ?  : a[alen-]-'0';
        int bbit = blen<= ?  : b[blen-]-'0';
        int cbit = carry ?  : ;
        result.insert(result.begin(), '0' + ((abit+bbit+cbit) & ) );
        carry = (abit+bbit+cbit>);
        alen--; blen--;
    }
    if (carry){
        result.insert(result.begin(), '1');
    }
    return result;
}

};