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Posted 19 Jan 2013
Licenced CPOL

Creating a Crossword Generator

, 11 Apr 2018
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Creating an application that can generate crosswords from a list of words


This article describes a simple application that can place a list of words, in either right-to-left or left-to-right language in a matrix, as a crossword.


A crossword is a word puzzle created from a grid of white and black squares, placing words horizontally and vertically on these squares while each two words which cross each other require having an identical letter at the place they are crossed.

The application described and included in this article is useful whenever there is a need to create a mechanism which will place words as a crossword, which would be the first step before composing clues and questions in which their answers will form these words.

The Application

While designing this application, there were several guidelines to comply with:

Supporting right-to-left languages, such as Hebrew. To comply with this requirement, words in such language go from right to left, when placed horizontally, and still, from top to bottom when placed vertically. Latin words are placed left to right, and from top to bottom.

Minimal distance between words placed at the same dimension. Two words placed horizontally or vertically one after the other will have at least one black square separating between the two.

An optimization process, used to find the optimal arrangement of any given set of words, which leave a minimum number of black square.

Loading words from a file, or placing them manually. The file should be an ASCII one, with one word per line.

The Code

The demo source code was created using C# and Visual Studio 2010.

There are several building blocks:

First, per each word about to be placed, we check if this place is valid:

bool IsValidPosition(int x , int y)
     return x >= 0 && y >= 0 && x < _n && y < _m;

Even if the position is valid, we also check if there is no other word crossing the word we are about to place, and if there is, the crossing point must have the same letter, both for the word placed horizontally and the word placed vertically.

int CanBePlaced(string word, int x, int y, int dir)
            var result = 0;
            if (dir == 0)
                for (var j = 0; j < word.Length; j++)
                    int x1 = x, y1 = y + j;
                    if (!(IsValidPosition(x1, y1) && (_board[x1, y1] == ' ' || 
                                                      _board[x1, y1] == word[j])))
                        return -1;
                    if (IsValidPosition(x1 - 1, y1))
                        if (_hWords[x1 - 1, y1] > 0)
                            return -1;
                    if (IsValidPosition(x1 + 1, y1))
                        if (_hWords[x1 + 1, y1] > 0)
                            return -1;
                    if (_board[x1, y1] == word[j])
                for (var j = 0; j < word.Length; j++)
                    int x1 = x + j, y1 = y;
                    if (!(IsValidPosition(x1, y1) && (_board[x1, y1] == ' ' || 
                                                      _board[x1, y1] == word[j])))
                        return -1;
                    if (IsValidPosition(x1, y1 - 1))
                        if (_vWords[x1, y1 - 1] > 0)
                            return -1;
                    if (IsValidPosition(x1, y1 + 1))
                        if (_vWords[x1, y1 + 1] > 0)
                            return -1;
                    if (_board[x1, y1] == word[j])
            int xStar = x - _dirX[dir], yStar = y - _dirY[dir];
            if (IsValidPosition(xStar, yStar))
                if (!(_board[xStar, yStar] == ' ' || _board[xStar, yStar] == '*'))
                    return -1;
            xStar = x + _dirX[dir]*word.Length;
            yStar = y + _dirY[dir]*word.Length;
            if (IsValidPosition(xStar, yStar))
                if (!(_board[xStar, yStar] == ' ' || _board[xStar, yStar] == '*'))
                    return -1;
            return result == word.Length ? -1 : result;

Then, when we actually place the word, we call:

void PutWord(string word , int x , int y , int dir, int value)
    var mat = dir==0 ? _hWords :_vWords;
    for (var i = 0; i < word.Length; i++)
        int x1 = x + _dirX[dir]*i, y1 = y + _dirY[dir]*i;
        _board[x1, y1] = word[i];
        mat[x1, y1] = value;
    int xStar = x - _dirX[dir], yStar = y - _dirY[dir];
    if (IsValidPosition(xStar, yStar)) _board[xStar, yStar] = '*';
    xStar = x + _dirX[dir]*word.Length;
    yStar = y + _dirY[dir]*word.Length;
    if (IsValidPosition(xStar, yStar)) _board[xStar, yStar] = '*';

This application is meant only for demonstration purposes. It creates a matrix of 13 X 17. The "Optimize" button tries to place the list of given words randomly while seeking for the optimal result for up to 1 minute. Obviously, this is not optimizing, and there can be many improvements, which will be more than welcome.

Michael Haephrati, CodeProject MVP 2013


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Michael Haephrati
CEO Secured Globe, Inc.
United States United States
Michael Haephrati, CEO and co-founder of Secured Globe, Inc. Worked on many ventures starting from HarmonySoft, designing Rashumon, the first Graphical Multi-lingual word processor for Amiga computer. During 1995-1996 he worked as a Contractor with Apple at Cupertino.

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Comments and Discussions

Questioni need a board of words without crosswords. Pin
Member 1351188320-Jan-19 6:29
memberMember 1351188320-Jan-19 6:29 
QuestionPuzzle size Pin
Member 802770514-Apr-18 4:47
memberMember 802770514-Apr-18 4:47 
QuestionVery cool Pin
RickKelleher12-Apr-18 11:31
memberRickKelleher12-Apr-18 11:31 
QuestionNot where real crossword creators start Pin
coderz212-Apr-18 6:37
membercoderz212-Apr-18 6:37 
QuestionGrids Pin
PeejayAdams12-Apr-18 4:46
memberPeejayAdams12-Apr-18 4:46 
Questionnice job Pin
Vinod Jangle11-Apr-18 9:58
memberVinod Jangle11-Apr-18 9:58 
Question[My vote of 2] Shouldn't all boxes be filled Pin
ovisariesdk29-May-17 5:23
memberovisariesdk29-May-17 5:23 
AnswerRe: [My vote of 2] Shouldn't all boxes be filled Pin
Michael Haephrati11-Jun-17 10:58
mvpMichael Haephrati11-Jun-17 10:58 
Questionoptimize button Pin
Member 122393382-Jan-16 11:49
memberMember 122393382-Jan-16 11:49 
AnswerRe: optimize button Pin
Michael Haephrati2-Jan-16 12:29
mvpMichael Haephrati2-Jan-16 12:29 
GeneralI LOVED!! Pin
Member 405343427-Mar-15 12:46
memberMember 405343427-Mar-15 12:46 
GeneralMy vote of 5 Pin
Joezer BH23-Jul-14 21:24
professionalJoezer BH23-Jul-14 21:24 
GeneralMy vote of 5 Pin
_Vitor Garcia_17-Jul-13 23:03
member_Vitor Garcia_17-Jul-13 23:03 
GeneralMy vote of 5 Pin
alonbarak14-Jun-13 12:10
groupalonbarak14-Jun-13 12:10 
GeneralMy vote of 5 Pin
Member 416352421-Feb-13 6:37
memberMember 416352421-Feb-13 6:37 
GeneralMy vote of 5 Pin
Roberto_4420-Mar-15 12:18
memberRoberto_4420-Mar-15 12:18 
GeneralMy vote of 5 Pin
Mihai MOGA16-Feb-13 20:16
professionalMihai MOGA16-Feb-13 20:16 
GeneralMy vote of 5 Pin
Boipelo16-Feb-13 6:52
memberBoipelo16-Feb-13 6:52 
QuestionCool Pin
i0015-Feb-13 4:19
member i0015-Feb-13 4:19 
AnswerRe: Cool Pin
i0029-Apr-13 19:25
member i0029-Apr-13 19:25 
GeneralMy vote of 5 Pin
Savalia Manoj M14-Feb-13 15:44
memberSavalia Manoj M14-Feb-13 15:44 
GeneralMy vote of 5 Pin
khanhamid92211-Feb-13 5:07
memberkhanhamid92211-Feb-13 5:07 
GeneralMy vote of 5 Pin
rumilal11-Feb-13 4:58
memberrumilal11-Feb-13 4:58 
GeneralGreat Pin
Anand Gunasekaran8-Feb-13 22:55
professionalAnand Gunasekaran8-Feb-13 22:55 
GeneralMy vote of 5 Pin
Monjurul Habib2-Feb-13 8:04
professionalMonjurul Habib2-Feb-13 8:04 

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