11988 - Broken Keyboard (a.k.a. Beiju Text) c++ implementation

Problem Type: C++ STL list (Java LinkedList)


Implementation:

#include<bits/stdc++.h>
using namespace std;
 /***
    Tarequzzaman Khan
    CSE'12
    2012331514
    */
int main()
{
    string s;
    while(cin >>s)
    {

        int tag =0;
        string sub="",output="";
        for(int i=0; i<s.length(); i++)
        {
            if(s[i]=='[')
            {
                tag =1;
                if(sub.compare("")!=0)
                {
                    output=sub + output;
                    sub ="";
                }
            }
            else if(s[i]==']')
            {
                tag = 0;
                if(sub.compare("")!=0)
                {
                    output=sub + output;
                    sub ="";
                }
            }
            else if(tag==1)
            {
                sub += s[i];
            }
            else
            {
                output += s[i];
            }
        }
        if(sub.compare("")!=0)
        {
         output = sub + output;
        }
        cout << output << endl;
    }
}