Problem Description

You are given a square letter  grid with a single word occupying the first row and column.  You are also given  a set  of letters to be used in completing the grid with intersecting words.  Each word will occur horizontally and vertically in the row and column of the same number.

At right is a partially completed 4x4 grid with the "Used letter" grid below it showing that 1 "E", 1 "F", and 2 "T"s need to be entered to complete the puzzle. .

Background & Techniques

This type of puzzle occurs several times in each year's Mensa Page-A-Day Puzzle Calendar.   They are usually not too difficult, but curiosity led me to try my hand at generating them.  The result is this puzzle program which creates 4x4 or 5x5 puzzles based on our medium size dictionary.  (The largest dictionary generates too many puzzles with words that most normal humans have never heard of.)  

Click the New Puzzle button to generate a random puzzle which will display the grid with the first word filled in.  As you click each square and enter a letter, the word grid and a second grid of the letter counts will be updated.     You may enter any valid letter in any square whether occupied or not in any cell except the first row or column,    The "Restart" button allows the user to reset letters and  statistics for the current puzzle.  Finally, the "Give Up button will display the solution that the program found.

Non-programmers are welcome to read on, but may want to skip to the bottom of this page to download executable version of the program.

Notes for Programmers

Our dictionary unit is used to generate the words for the puzzle.  For efficiency, all words of   the desired length are extracted to a TStringList named List.     The initial word is selected randomly and a call made to the recursive FIndNextWord function to fill in the rest of the words.   FindNextWord  tries up to 1000  random words to find one which would fit with the preceding words already selected.  After 1000 tries, we resort to a sequential search through the list looking for qualifying words.   The idea of random selection is to increase the number of puzzles generated even when the initial word has been used in a previous puzzle.

 Words as found are kept in a array, of strings W.  The initial word is placed the TstringGrid, Lettergrid.  A second TStringgrid, StatsGrid, contains 3 rows of available letters, the available count for each  letter, and the count of times that letter was entered by the user.

Lettergrid has an OnKeyPress exit which handles each user click.   Only letters from the   valid letter set are allowed and they may be be placed in the 1st column or row.  Letters off of the diagonal  are automatically duplicated in the corresponding position on the other side of the diagonal. After each letter is placed, the letter counts in the Statsgrid are updated, and if all letters have been used, a check is made for a valid solution.   In testing, I found cases where the solution was not unique.  The posted version checks the users words against the list of all words as well as against the solution found by the program.  Credit for solving is given  for solutions, whether or not they match the one found by the program, however in the "new solution" case, the user is informed that there is more than one solution.      .

Running/Exploring the Program 

Suggestions for Further Explorations

A useful option would be to allow user to select the dictionary to use.  The current dictionary, General.dic is medium sized and has only a couple of thousand 4 letter words.  Those with an initial vowel must be quite limited, since I tend to see "AREA", "IRIS", and "OKRA" with greater frequency than one would expect.    Perhaps a version with more of these initial-vowel words should be generated.  (The full dictionary has too many esoteric words to be fair or fun for the player.  but there are probably many common words that could augment the word list used .)

A better reward for success would be nice.  Sound or visual effects are good but tend to increase program size significantly.   A serious version of the program might allow the user customize the type and specific files used for rewards.