contrib/lisp/org-sudoku.el

   1 ;;; org-sudoku.el --- Greate and solve SUDOKU games in Org tables
   2
   3 ;; Copyright (C) 2012 Free Software Foundation, Inc.
   4 ;;
   5 ;; Author: Carsten Dominik <carsten at orgmode dot org>
   6 ;; Keywords: outlines, hypermedia, calendar, wp, games
   7 ;; Homepage: http://orgmode.org
   8 ;; Version: 0.01
   9 ;;
  10 ;; This file is not yet part of GNU Emacs.
  11 ;;
  12 ;; GNU Emacs is free software; you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation; either version 3, or (at your option)
  15 ;; any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  25 ;; Boston, MA 02110-1301, USA.
  26 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  27 ;;
  28 ;;; Commentary:
  29 ;;
  30 ;; This is a quick hack to create and solve SUDOKU games in org tables.
  31 ;;
  32 ;; Commands:
  33 ;;
  34 ;; org-sudoku-create         Create a new SUDOKU game
  35 ;; org-sudoku-solve-field    Solve the field at point in a SUDOKU game
  36 ;;                           (this is for cheeting when you are stuck)
  37 ;; org-sudoku-solve          Solve the entire game
  38 ;;
  39
  40 ;;; Code
  41
  42 (require 'org)
  43 (require 'org-table)
  44
  45 ;;; Customization
  46
  47 (defvar org-sudoku-size 9
  48   "The size of the sudoku game, 9 for a 9x9 game and 4 for a 4x4 game.
  49 Larger games do not seem to work because of limited resources - even though
  50 the algorithm is general.")
  51
  52 (defvar org-sudoku-timeout 2.0
  53   "Timeout for finding a solution when creating a new game.
  54 After this timeout, the program starts over from scratch to create
  55 a game.")
  56
  57 ;;; Interactive commands
  58
  59 (defun org-sudoku-create (nfilled)
  60   "Create a sudoku game."
  61   (interactive "nNumber of pre-filled fields: ")
  62   (let ((sizesq org-sudoku-size)
  63         game)
  64     (loop for i from 1 to org-sudoku-size do
  65           (loop for j from 1 to org-sudoku-size do
  66                 (push (list (cons i j) 0) game)))
  67     (setq game (nreverse game))
  68     (random t)
  69     (setq game (org-sudoku-build-allowed game))
  70     (setq game (org-sudoku-set-field game (cons 1 1)
  71                                      (1+ (random org-sudoku-size))))
  72     (catch 'solved
  73       (let ((cnt 0))
  74         (while t
  75           (catch 'abort
  76             (message "Attempt %d to create a game" (setq cnt (1+ cnt)))
  77             (setq game1 (org-sudoku-deep-copy game))
  78             (setq game1 (org-sudoku-solve-game
  79                          game1 'random (+ (float-time) org-sudoku-timeout)))
  80             (when game1
  81               (setq game game1)
  82               (throw 'solved t))))))
  83     (let ((sqrtsize (floor (sqrt org-sudoku-size))))
  84       (loop for i from 1 to org-sudoku-size do
  85             (insert "| |\n")
  86             (if (and (= (mod i sqrtsize) 0) (< i org-sudoku-size))
  87                 (insert "|-\n")))
  88       (backward-char 5)
  89       (org-table-align))
  90     (while (> (length game) nfilled)
  91       (setq game (delete (nth (1+ (random (length game))) game) game)))
  92     (mapc (lambda (e)
  93             (org-table-put (caar e) (cdar e) (int-to-string (nth 1 e))))
  94           game)
  95     (org-table-align)
  96     (org-table-goto-line 1)
  97     (org-table-goto-column 1)
  98     (message "Enjoy!")))
  99
 100 (defun org-sudoku-solve ()
 101   "Solve the sudoku game in the table at point."
 102   (interactive)
 103   (unless (org-at-table-p)
 104     (error "not at a table"))
 105   (let (game)
 106     (setq game (org-sudoku-get-game))
 107     (setq game (org-sudoku-build-allowed game))
 108     (setq game (org-sudoku-solve-game game))
 109     ;; Insert the values
 110     (mapc (lambda (e)
 111             (org-table-put (caar e) (cdar e) (int-to-string (nth 1 e))))
 112           game)
 113     (org-table-align)))
 114
 115 (defun org-sudoku-solve-field ()
 116   "Just solve the field at point.
 117 This works by solving the whole game, then inserting only the single field."
 118   (interactive)
 119   (unless (org-at-table-p)
 120     (error "Not at a table"))
 121   (org-table-check-inside-data-field)
 122   (let ((i (org-table-current-dline))
 123         (j (org-table-current-column))
 124         game)
 125     (setq game (org-sudoku-get-game))
 126     (setq game (org-sudoku-build-allowed game))
 127     (setq game (org-sudoku-solve-game game))
 128     (if game
 129         (progn
 130           (org-table-put i j (number-to-string
 131                               (nth 1 (assoc (cons i j) game)))
 132                          'align)
 133           (org-table-goto-line i)
 134           (org-table-goto-column j))
 135       (error "No solution"))))
 136
 137 ;;; Internal functions
 138
 139 (defun org-sudoku-get-game ()
 140   "Interpret table at point as sudoku game and read it.
 141 A game structure is returned."
 142   (let (b e g i j game)
 143
 144     (org-table-goto-line 1)
 145     (org-table-goto-column 1)
 146     (setq b (point))
 147     (org-table-goto-line org-sudoku-size)
 148     (org-table-goto-column org-sudoku-size)
 149     (setq e (point))
 150     (setq g (org-table-copy-region b e))
 151     (setq i 0 j 0)
 152     (mapc (lambda (c)
 153             (setq i (1+ i) j 0)
 154             (mapc
 155              (lambda (v)
 156                (setq j (1+ j))
 157                (push (list (cons i j)
 158                            (string-to-number v))
 159                      game))
 160              c))
 161           g)
 162     (nreverse game)))
 163
 164 (defun org-sudoku-build-allowed (game)
 165   (let (i j v numbers)
 166     (loop for i from 1 to org-sudoku-size do
 167           (push i numbers))
 168     (setq numbers (nreverse numbers))
 169     ;; add the lists of allowed values for each entry
 170     (setq game (mapcar
 171                 (lambda (e)
 172                   (list (car e) (nth 1 e)
 173                         (if (= (nth 1 e) 0)
 174                             (copy-sequence numbers)
 175                           nil)))
 176                 game))
 177     ;; remove the known values from the list of allowed values
 178     (mapc
 179      (lambda (e)
 180        (setq i (caar e) j (cdar e) v (cadr e))
 181        (when (> v 0)
 182          ;; We do have a value here
 183          (mapc
 184           (lambda (f)
 185             (setq a (assoc f game))
 186             (setf (nth 2 a) (delete v (nth 2 a))))
 187           (cons (cons i j) (org-sudoku-rel-fields i j)))))
 188      game)
 189     game))
 190
 191 (defun org-sudoku-find-next-constrained-field (game)
 192   (setq game (mapcar (lambda (e) (if (nth 2 e) e nil)) game))
 193   (setq game (delq nil game))
 194   (let (va vb la lb)
 195     (setq game
 196           (sort game (lambda (a b)
 197                        (setq va (nth 1 a) vb (nth 1 b)
 198                              la (length (nth 2 a)) lb (length (nth 2 b)))
 199                        (cond
 200                         ((and (= va 0) (> vb 0)) t)
 201                         ((and (> va 0) (= vb 0)) nil)
 202                         ((not (= (* va vb) 0)) nil)
 203                         (t (< la lb))))))
 204     (if (or (not game) (> 0 (nth 1 (car game))))
 205         nil
 206       (caar game))))
 207
 208 (defun org-sudoku-solve-game (game &optional random stop-at)
 209   "Solve GAME.
 210 If RANDOM is non-nit, select candidates randomly from a fields option.
 211 If RANDOM is nil, always start with the first allowed value and try
 212 solving from there.
 213 STOP-AT can be a float time, the solver will abort at that time because
 214 it is probably stuck."
 215   (let (e v v1 allowed next g)
 216     (when (and stop-at
 217                (> (float-time) stop-at))
 218       (setq game nil)
 219       (throw 'abort nil))
 220     (while (setq next (org-sudoku-find-next-constrained-field game))
 221       (setq e (assoc next game)
 222             v (nth 1 e)
 223             allowed (nth 2 e))
 224       (catch 'solved
 225         (if (= (length allowed) 1)
 226             (setq game (org-sudoku-set-field game next (car allowed)))
 227           (while allowed
 228             (setq g (org-sudoku-deep-copy game))
 229             (if (not random)
 230                 (setq v1 (car allowed))
 231               (setq v1 (nth (random (length allowed)) allowed)))
 232             (setq g (org-sudoku-set-field g next v1))
 233             (setq g (org-sudoku-solve-game g random stop-at))
 234             (when g
 235               (setq game g)
 236               (throw 'solved g)))
 237           (setq game nil))))
 238     (if (or (not game)
 239             (org-sudoku-unknown-field-p game))
 240         nil
 241       game)))
 242
 243 (defun org-sudoku-unknown-field-p (game)
 244   "Are there still unknown fields in the game?"
 245   (delq nil (mapcar (lambda (e) (if (> (nth 1 e) 0) nil t)) game)))
 246
 247 (defun org-sudoku-deep-copy (game)
 248   "Make a copy of the game so that manipulating the copy does not change the parent."
 249   (mapcar (lambda(e)
 250             (list (car e) (nth 1 e) (copy-sequence (nth 2 e))))
 251           game))
 252
 253 (defun org-sudoku-set-field (game field value)
 254   "Put VALUE into FIELD, and tell related fields that they cannot be VALUE."
 255   (let (i j)
 256     (setq i (car field) j (cdr field))
 257     (setq a (assoc field game))
 258     (setf (nth 1 a) value)
 259     (setf (nth 2 a) nil)
 260
 261     ;; Remove value from all related fields
 262     (mapc
 263      (lambda (f)
 264        (setq a (assoc f game))
 265        (setf (nth 2 a) (delete value (nth 2 a))))
 266      (org-sudoku-rel-fields i j))
 267     game))
 268
 269 (defun org-sudoku-rel-fields (i j)
 270   "Compute the list of related fields for field (i j)."
 271   (let ((sqrtsize (floor (sqrt org-sudoku-size)))
 272         ll imin imax jmin jmax f)
 273     (setq f (cons i j))
 274     (loop for ii from 1 to org-sudoku-size do
 275           (or (= ii i) (push (cons ii j) ll)))
 276     (loop for jj from 1 to org-sudoku-size do
 277           (or (= jj j) (push (cons i jj) ll)))
 278     (setq imin (1+ (* sqrtsize (/ (1- i) sqrtsize)))
 279           imax (+ imin sqrtsize -1))
 280     (setq jmin (1+ (* sqrtsize (/ (1- j) sqrtsize)))
 281           jmax (+ jmin sqrtsize -1))
 282     (loop for ii from imin to imax do
 283           (loop for jj from jmin to jmax do
 284                 (setq ff (cons ii jj))
 285                 (or (equal ff f)
 286                     (member ff ll)
 287                     (push ff ll))))
 288     ll))
 289
 290 ;;; org-sudoku ends here