leetcode-com-explore-challenge-card-july-leetcoding-challenge-546-week-3-july-15th-july-21st-3395.cpp

class Solution {
public:
    string addBinary(string a, string b) {
        int i = a.size()-1;
        int j = b.size()-1;
    int carry = 0;
    string ret = "";
        
    while (i >= 0 || j >= 0 || carry!=0) {
        if (i >= 0) {
            carry += a[i]=='0'?0:1;
            i--;
        }
        if (j >= 0) {
            carry += b[j]=='0'?0:1;
            j--;
        }
        ret = ((carry%2)==0?"0":"1") + ret;
        carry /= 2;
    }
    return ret;
    }
};