UVA_11988_Broken_Keyboard

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <cctype>
#include <stack>
#include <queue>
#include <list>
#include <vector>
#include <map>
#include <set>
#include <sstream>
#include <stdlib.h>
#include <cmath>
#define LL unsigned long long
#define N 1000000
using namespace std;
char input [N];


int main ()
{
    while ( scanf ("%s", input) != EOF ) {

        int len = strlen (input);

        list <char> output;

        list <char>::iterator it = output.begin();

        for ( int i = 0; i < len; i++ ) {

            if ( input [i] == '[' ) it = output.begin();
            else if ( input [i] == ']' ) it = output.end();
            else output.insert(it, input [i]);
        }

        for ( it = output.begin(); it != output.end(); it++ )
            printf ("%c", *it);

        printf ("\n");
    }

    return 0;
}