Facebook Hacker Cup 2013: “Balanced Smileys” Solution
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.
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
Here goes my solution for the “Beautiful Strings” problem:
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"; } }
Download Source Code Here
The solution is quite efficient and generated output file for my input file provided by Facebook in less than one second.
Do leave comment regarding any issue or suggestion.
is this message '(first) (second)' had balanced parentheses?
ReplyDeleteyeah ofcourse, A message with balanced parentheses followed by another message with balanced parentheses is balanced... :D
ReplyDeletecoool! running your code give as result: "Case #1: NO"
ReplyDeleteSorry for the bad news, but this case breaks your program: () :( ()
ReplyDeleteIf we consider the middle smiley face as a "real" smiley, then it would be balanced. Sorry again, better luck next time.
@Tonynater, in this case you can not take middle :( as smiley, you have to first check for the balanced parenthesis and then for smileys. If you have a string consisting of colon and parenthesis then you have to first check out for parenthesis and not smileys as you can see the last condition for balanced smileys.
ReplyDeleteBut your program prints "NO" when it should be "YES". Am I correct?
ReplyDeleteThe above program doesnt report the correct output for "(()):):)"
ReplyDelete