Below is the problem statement for 'Tic-Tac-Toe-Tomek' from 'Google Code Jam - 2013':
Tic-Tac-Toe-Tomek is a game played on a 4 x 4 square board. The board starts empty, except that a single 'T' symbol may appear in one of the 16 squares. There are two players: X and O. They take turns to make moves, with X starting. In each move a player puts her symbol in one of the empty squares. Player X's symbol is 'X', and player O's symbol is 'O'.
After a player's move, if there is a row, column or a diagonal containing 4 of that player's symbols, or containing 3 of her symbols and the 'T' symbol, she wins and the game ends. Otherwise the game continues with the other player's move. If all of the fields are filled with symbols and nobody won, the game ends in a draw. See the sample input for examples of various winning positions.
Given a 4 x 4 board description containing 'X', 'O', 'T' and '.' characters (where '.' represents an empty square), describing the current state of a game, determine the status of the Tic-Tac-Toe-Tomek game going on. The statuses to choose from are:
"X won" (the game is over, and X won)
"O won" (the game is over, and O won)
"Draw" (the game is over, and it ended in a draw)
"Game has not completed" (the game is not over yet)
If there are empty cells, and the game is not over, you should output "Game has not completed", even if the outcome of the game is inevitable.
The first line of the input gives the number of test cases, T. T test cases follow. Each test case consists of 4 lines with 4 characters each, with each character being 'X', 'O', '.' or 'T' (quotes for clarity only). Each test case is followed by an empty line.
For each test case, output one line containing "Case #x: y", where x is the case number (starting from 1) and y is one of the statuses given above. Make sure to get the statuses exactly right. When you run your code on the sample input, it should create the sample output exactly, including the "Case #1: ", the capital letter "O" rather than the number "0", and so on.
The game board provided will represent a valid state that was reached through play of the game Tic-Tac-Toe-Tomek as described above.
1 ≤ T ≤ 10.
1 ≤ T ≤ 1000.
Case #1: X won
Case #2: Draw
Case #3: Game has not completed
Case #4: O won
Case #5: O won
Case #6: O won
From the above problem statement, it is clear that we have to check all the rows, columns and diagonals to determine the status of the game. Since it's a small 4*4 board, it was easy for me to build a set of constant strings, which will help my program decide the status of the game. For X to win, the possible set of winning combination strings are: XXXX, XXXT, XXTX, XTXX, TXXX. Similarly, for O to win, the possible set of winning combination strings are: OOOO, OOOT, OOTO, OTOO, TOOO. After knowing this, it was easy for me to loop through rows, columns and diagonals, to determine the status of the game.
Initially, that was the logic (above paragraph) for my solution. After I re-read the problem statement, I wrongly assumed that I have to determine the status of the game, after the next step (future). So, I changed my code to find out who's gonna make the next move (by counting the number of X's and O's - If they are equal, X moves, otherwise O moves) and tried to find the status of the game, after the next step. This was obviously wrong...So, I reverted back to my old code. Here's the solution for the above problem statement:
In the below solution, I'm parsing the input from the file and storing the String input (rows) in an String array of length 4 and passing it to the getStatusQuo method, as shown in the below code:
You can also find the source code at: GCJ 2013 - TicTacToeTomek