Maximum Odd Binary Number

class Solution {
public:
    string maximumOddBinaryNumber(string s) {
        int k = 0;
        for(int i = 0; i < s.size(); ++i) {
            if(s[i] == '1') swap(s[k ++], s[i]);
        }
        swap(s[k - 1], s.back());
        return s;
    }
};