pliesveld / scramblesearch

A search algorithm for a popular word game

ScrambleSearch

Description

Scramble with Friends™ is a word game played on a 4x4 grid of letters. The player forms words from letters, and may only use each tile once per word. The word score is computed from three sources: the summation tiles' letter, a bonus for words atleast five letters, and special tiles that add multipliers to the letter or word.

Search

This programs reads the dictionary file enable1.txt, and maintains a HashSet for fast lookup. The board is read from the standard input horizontally, accepting the first 16 letters. To denote a tile that is a double or triple letter bonus, immediately append +2 or +3 respectively. Similiarly, *2 and *3 represents double and triple word.

A player may start constructing a word from any Tile. All initial starting Locations are inserted into a fringe queue.

        for(int i = 0; i < MAX_BOARD_WIDTH; ++i)
            for(int j = 0; j < MAX_BOARD_HEIGHT; ++j)
                fringe.add(new State(Scramble.board,new Location(j,i)));

To form words, the player constructs words from adjacent letters. State is kept that maintains the Location of the current Tile, the word constructed so far, the word score, the available Actions. An Action is the cardinal direction of the adjacent Tile from the State's current Tile. The available actions from a given State are constrainted by the current and prior Locations. That is to say, that no Action would be available to a State that would result in an invalid Location outside the board, or select a Tile that has already been selected in the sequence of States the preceeded.

The next State is one that has advanced the current Location by an Action. For each available Action to a State, a new State is created and added back to the fringe queue.

        void find_words()
        {
            State s;
            WordList found = new WordList();
            while (( s = fringe.poll()) != null)
            {

                String w = s.getWord();
                if(dict.isWord(w))
                    found.add(w,s.getScore());

                LinkedList<State> next_states = new LinkedList<State>();

                for(Action a : s.available_actions())
                    next_states.add(s.next(a));

                for(State ns : next_states)
                    fringe.push(ns);
            }
	    ...

The State also maintains the score of the tiles used to construct the words. The WordList containing the matching words is a priority queue sorted by score.

Environment Variables

MIN_WORD_SIZE Words less than this value are not reported.

MAX_WORD_SIZE States that construct words longer than this value are not explored.

SCORE displays next to the word its score

Example

$ javac src/ScrambleSearchApp.java
$ MIN_WORD_SIZE=8 java -cp src/ ScrambleSearchApp <<EOF
c*2eybh+2nsee+3a+3rddteu
EOF

Board:
c*2	e	y	b	
h+2	n	s	e	
e+3	a+3	r	d	
d	t	e	u	

detrudes
durances
enchaser
tranches
enchased
cheaters
Found: 6

Scramble with Friends™ is a registered trademark of Zynga, for which this has no affiliation.