Leetcode 67: Add Binary

leetcode_67.cpp

#include <iostream>
#include <string>

using namespace std;

string addBinary(string a, string b) {
    string result(max(a.size(), b.size()), '0');
    int carry=0, k=result.size()-1;
    for (int i=a.size()-1, j=b.size()-1; i>=0 || j>=0; --i,--j) {
        int sum = 0;
        if (i>=0) sum += (a[i]-'0');
        if (j>=0) sum += (b[j]-'0');
        sum += carry;
        carry = 0;
        if (sum>1) {
            carry = 1;
            sum -= 2;
        }
        result[k--] = ('0'+sum);
    }
    if (carry > 0)
        result.insert(result.begin(), '1');
    return result;
}

int main() {
    cout << addBinary("1010", "1011") << "\n";
    return 0;
}