class Solution {

public:

    bool backspaceCompare(string S, string T) {

        return backspace(S)==backspace(T);

    }

    string backspace(string str)

    {

        string res ="";

        for(auto ch:str)

        {

            if(ch=='#')

            {

                if(!res.empty()) res.pop_back();

            }

            else res.push_back(ch);

        }

        return res;

    }

};

class Solution {

public:

    bool backspaceCompare(string S, string T) {

        string s = "", t = "";

        for(auto ch:S) ch=='#' ? (s.empty()? void():s.pop_back()) : s.push_back(ch);//err...

        for(auto ch:T) ch=='#' ? (t.empty()? void():t.pop_back()) : t.push_back(ch);

        return s==t;

    }

};