394-decode-string.cpp

class Solution {
public:
    string decodeString(string s) {
        stack <string> stk;
        string sub, word, num;
        for (int i=0; i<s.length(); i++){
            // cout << s[i];
            if (s[i] == ']'){
                sub = "";
                word = "";
                while(stk.top() != "["){
                    sub = stk.top() + sub;
                    stk.pop();
                    cout << "$ " << sub << endl;
                };
                stk.pop();
                num = "";
                while (stk.top() <= "9" && stk.top()>="0"){
                    num = stk.top() + num;
                    cout << "$ " << num << endl;
                    stk.pop();
                    if (stk.empty()) break;
                }
                cout << endl <<num;
                int rep = stoi(num);
                while (rep--)
                    word += sub;
                stk.push(word);
                cout << "# " << word << endl;
                continue;
            }
            stk.push(string(1,s[i]));
        }
        string res = "";
        while (!(stk.empty())){
            res = stk.top() + res;
            stk.pop();    
        }
        return res;
    }
};