This is my solution for Facebook Hacker Cup 2013 in java :Balanced Smileys

Facebook Hacker Cup 2013 Solution : Balanced Smileys

The problem statement is given below:

Your friend John uses a lot of emoticons when you talk to him on Messenger. In addition to being a person who likes to express himself through emoticons, he hates unbalanced parenthesis so much that it makes him go :(
Sometimes he puts emoticons within parentheses, and you find it hard to tell if a parenthesis really is a parenthesis or part of an emoticon.
A message has balanced parentheses if it consists of one of the following:
1.  An empty string ""
2. One or more of the following characters: 'a' to 'z', ' ' (a space) or ':' (a colon)
3.  An open parenthesis '(', followed by a message with balanced parentheses, followed by a close parenthesis ')'.
4. A message with balanced parentheses followed by another message with balanced parentheses.
5. A smiley face ":)" or a frowny face ":("
Write a program that determines if there is a way to interpret his message while leaving the parentheses balanced.
Input

The first line of the input contains a number T (1 ≤ T ≤ 50), the number of test cases. 
The following T lines each contain a message of length s that you got from John.

Output

For each of the test cases numbered in order from 1 to T, output "Case #i: " followed by a string stating whether or not it is possible that the message had balanced parentheses. If it is, the string should be "YES", else it should be "NO" (all quotes for clarity only)

Constraints
1 ≤ length of s ≤ 100
Sample Input
5
:((
i am sick today (:()
(:)
hacker cup: started :):)
)(
Sample Output
Case #1: NO
Case #2: YES
Case #3: YES
Case #4: YES
Case #5: NO

Facebook Hacker Cup Solution in java of problem Balanced Smileys

//Please visit: http://vikash-thiswillgoaway.blogspot.in/2013/01/facebook-hacker-cup-2013-balanced.html for the solutions
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.LineNumberReader;
import java.util.ArrayList;

/**
 *
 * @author VIK http://www.facebook.com/vikashvverma
 * 
 */
public class Problem2 {

    private static File f = new File("Solution2.txt");

    public static void main(String[] args) throws Exception {
        FileReader fr = new FileReader("balanced_smileystxt.txt");
        LineNumberReader lnr = new LineNumberReader(fr);
        int t = Integer.parseInt(lnr.readLine().trim());
        ArrayList < String > list = new ArrayList < String >();
        FileWriter fw = new FileWriter(f);
        for (int i = 0; i < t; i++) {
            list.add(lnr.readLine().trim());
            String res = printResult(list.get(i), i + 1);
            if ( i < t - 1 ) {
                fw.write("Case #" + (i + 1) + ": " + res + "\n");
            } else {
                fw.write("Case #" + (i + 1) + ": " + res);
            }
            fw.flush();
        }

    }

    private static String printResult(String string, int index) {
        String s = string.replaceAll( "[^:\\(\\)]", "" );

        for (int i = 0; i < s.length() / 2; i++) {
            String lead = "";
            String trail = "";
            if (s.charAt(i) == '(' && s.charAt(s.length() - i - 1) == ')') {
                if (i > 0) {
                    lead = s.substring(0, i);
                    trail = s.substring(s.length() - i, s.length());
                }
                s = lead + s.substring(i + 1, s.length() - i - 1) + trail;
                --i;
            }
        }
        s = s.replaceAll( ":\\(", "" );
        s = s.replaceAll( ":\\)", "" );

        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) == '(' || s.charAt(i) == ')') {
                return "NO";
            }
        }

        return "YES";
     }
}

Regular expression :) How about the third problem?

I would think its a bad idea to post the solution of problem when the competition is going on. Not only you are in position to be disqualified for this competition, they may bar you in future competitions also.

It fails.

Why would you post this when the competition is still not finished?

On a general note you can try using java.util.Scanner to read files.