289 lines
8.7 KiB
EmacsLisp
289 lines
8.7 KiB
EmacsLisp
;;; org-sudoku.el --- Create and solve SUDOKU games in Org tables
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;; Copyright (C) 2012-2021 Free Software Foundation, Inc.
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;;
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;; Author: Carsten Dominik <carsten at orgmode dot org>
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;; Keywords: outlines, hypermedia, calendar, wp, games
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;; Homepage: https://orgmode.org
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;; Version: 0.01
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;;
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;; This file is not yet part of GNU Emacs.
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;;
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;; This program is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 3, or (at your option)
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;; any later version.
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;; This program is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;
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;;; Commentary:
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;;
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;; This is a quick hack to create and solve SUDOKU games in org tables.
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;;
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;; Commands:
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;;
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;; org-sudoku-create Create a new SUDOKU game
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;; org-sudoku-solve-field Solve the field at point in a SUDOKU game
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;; (this is for cheeting when you are stuck)
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;; org-sudoku-solve Solve the entire game
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;;
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;;; Code
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(require 'org)
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(require 'org-table)
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;;; Customization
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(defvar org-sudoku-size 9
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"The size of the sudoku game, 9 for a 9x9 game and 4 for a 4x4 game.
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Larger games do not seem to work because of limited resources - even though
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the algorithm is general.")
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(defvar org-sudoku-timeout 2.0
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"Timeout for finding a solution when creating a new game.
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After this timeout, the program starts over from scratch to create
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a game.")
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;;; Interactive commands
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(defun org-sudoku-create (nfilled)
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"Create a sudoku game."
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(interactive "nNumber of pre-filled fields: ")
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(let ((sizesq org-sudoku-size)
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game)
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(loop for i from 1 to org-sudoku-size do
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(loop for j from 1 to org-sudoku-size do
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(push (list (cons i j) 0) game)))
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(setq game (nreverse game))
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(random t)
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(setq game (org-sudoku-build-allowed game))
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(setq game (org-sudoku-set-field game (cons 1 1)
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(1+ (random org-sudoku-size))))
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(catch 'solved
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(let ((cnt 0))
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(while t
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(catch 'abort
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(message "Attempt %d to create a game" (setq cnt (1+ cnt)))
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(setq game1 (org-sudoku-deep-copy game))
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(setq game1 (org-sudoku-solve-game
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game1 'random (+ (float-time) org-sudoku-timeout)))
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(when game1
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(setq game game1)
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(throw 'solved t))))))
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(let ((sqrtsize (floor (sqrt org-sudoku-size))))
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(loop for i from 1 to org-sudoku-size do
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(insert "| |\n")
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(if (and (= (mod i sqrtsize) 0) (< i org-sudoku-size))
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(insert "|-\n")))
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(backward-char 5)
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(org-table-align))
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(while (> (length game) nfilled)
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(setq game (delete (nth (1+ (random (length game))) game) game)))
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(mapc (lambda (e)
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(org-table-put (caar e) (cdar e) (int-to-string (nth 1 e))))
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game)
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(org-table-align)
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(org-table-goto-line 1)
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(org-table-goto-column 1)
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(message "Enjoy!")))
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(defun org-sudoku-solve ()
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"Solve the sudoku game in the table at point."
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(interactive)
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(unless (org-at-table-p)
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(error "not at a table"))
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(let (game)
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(setq game (org-sudoku-get-game))
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(setq game (org-sudoku-build-allowed game))
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(setq game (org-sudoku-solve-game game))
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;; Insert the values
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(mapc (lambda (e)
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(org-table-put (caar e) (cdar e) (int-to-string (nth 1 e))))
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game)
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(org-table-align)))
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(defun org-sudoku-solve-field ()
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"Just solve the field at point.
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This works by solving the whole game, then inserting only the single field."
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(interactive)
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(unless (org-at-table-p)
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(error "Not at a table"))
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(org-table-check-inside-data-field)
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(let ((i (org-table-current-dline))
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(j (org-table-current-column))
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game)
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(setq game (org-sudoku-get-game))
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(setq game (org-sudoku-build-allowed game))
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(setq game (org-sudoku-solve-game game))
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(if game
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(progn
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(org-table-put i j (number-to-string
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(nth 1 (assoc (cons i j) game)))
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'align)
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(org-table-goto-line i)
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(org-table-goto-column j))
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(error "No solution"))))
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;;; Internal functions
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(defun org-sudoku-get-game ()
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"Interpret table at point as sudoku game and read it.
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A game structure is returned."
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(let (b e g i j game)
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(org-table-goto-line 1)
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(org-table-goto-column 1)
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(setq b (point))
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(org-table-goto-line org-sudoku-size)
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(org-table-goto-column org-sudoku-size)
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(setq e (point))
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(setq g (org-table-copy-region b e))
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(setq i 0 j 0)
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(mapc (lambda (c)
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(setq i (1+ i) j 0)
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(mapc
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(lambda (v)
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(setq j (1+ j))
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(push (list (cons i j)
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(string-to-number v))
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game))
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c))
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g)
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(nreverse game)))
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(defun org-sudoku-build-allowed (game)
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(let (i j v numbers)
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(loop for i from 1 to org-sudoku-size do
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(push i numbers))
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(setq numbers (nreverse numbers))
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;; add the lists of allowed values for each entry
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(setq game (mapcar
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(lambda (e)
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(list (car e) (nth 1 e)
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(if (= (nth 1 e) 0)
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(copy-sequence numbers)
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nil)))
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game))
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;; remove the known values from the list of allowed values
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(mapc
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(lambda (e)
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(setq i (caar e) j (cdar e) v (cadr e))
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(when (> v 0)
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;; We do have a value here
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(mapc
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(lambda (f)
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(setq a (assoc f game))
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(setf (nth 2 a) (delete v (nth 2 a))))
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(cons (cons i j) (org-sudoku-rel-fields i j)))))
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game)
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game))
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(defun org-sudoku-find-next-constrained-field (game)
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(setq game (mapcar (lambda (e) (if (nth 2 e) e nil)) game))
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(setq game (delq nil game))
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(let (va vb la lb)
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(setq game
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(sort game (lambda (a b)
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(setq va (nth 1 a) vb (nth 1 b)
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la (length (nth 2 a)) lb (length (nth 2 b)))
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(cond
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((and (= va 0) (> vb 0)) t)
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((and (> va 0) (= vb 0)) nil)
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((not (= (* va vb) 0)) nil)
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(t (< la lb))))))
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(if (or (not game) (> 0 (nth 1 (car game))))
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nil
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(caar game))))
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(defun org-sudoku-solve-game (game &optional random stop-at)
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"Solve GAME.
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If RANDOM is non-nit, select candidates randomly from a fields option.
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If RANDOM is nil, always start with the first allowed value and try
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solving from there.
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STOP-AT can be a float time, the solver will abort at that time because
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it is probably stuck."
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(let (e v v1 allowed next g)
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(when (and stop-at
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(> (float-time) stop-at))
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(setq game nil)
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(throw 'abort nil))
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(while (setq next (org-sudoku-find-next-constrained-field game))
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(setq e (assoc next game)
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v (nth 1 e)
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allowed (nth 2 e))
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(catch 'solved
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(if (= (length allowed) 1)
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(setq game (org-sudoku-set-field game next (car allowed)))
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(while allowed
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(setq g (org-sudoku-deep-copy game))
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(if (not random)
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(setq v1 (car allowed))
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(setq v1 (nth (random (length allowed)) allowed)))
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(setq g (org-sudoku-set-field g next v1))
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(setq g (org-sudoku-solve-game g random stop-at))
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(when g
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(setq game g)
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(throw 'solved g)))
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(setq game nil))))
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(if (or (not game)
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(org-sudoku-unknown-field-p game))
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nil
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game)))
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(defun org-sudoku-unknown-field-p (game)
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"Are there still unknown fields in the game?"
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(delq nil (mapcar (lambda (e) (if (> (nth 1 e) 0) nil t)) game)))
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(defun org-sudoku-deep-copy (game)
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"Make a copy of the game so that manipulating the copy does not change the parent."
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(mapcar (lambda(e)
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(list (car e) (nth 1 e) (copy-sequence (nth 2 e))))
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game))
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(defun org-sudoku-set-field (game field value)
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"Put VALUE into FIELD, and tell related fields that they cannot be VALUE."
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(let (i j)
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(setq i (car field) j (cdr field))
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(setq a (assoc field game))
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(setf (nth 1 a) value)
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(setf (nth 2 a) nil)
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;; Remove value from all related fields
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(mapc
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(lambda (f)
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(setq a (assoc f game))
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(setf (nth 2 a) (delete value (nth 2 a))))
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(org-sudoku-rel-fields i j))
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game))
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(defun org-sudoku-rel-fields (i j)
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"Compute the list of related fields for field (i j)."
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(let ((sqrtsize (floor (sqrt org-sudoku-size)))
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ll imin imax jmin jmax f)
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(setq f (cons i j))
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(loop for ii from 1 to org-sudoku-size do
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(or (= ii i) (push (cons ii j) ll)))
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(loop for jj from 1 to org-sudoku-size do
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(or (= jj j) (push (cons i jj) ll)))
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(setq imin (1+ (* sqrtsize (/ (1- i) sqrtsize)))
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imax (+ imin sqrtsize -1))
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(setq jmin (1+ (* sqrtsize (/ (1- j) sqrtsize)))
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jmax (+ jmin sqrtsize -1))
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(loop for ii from imin to imax do
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(loop for jj from jmin to jmax do
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(setq ff (cons ii jj))
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(or (equal ff f)
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(member ff ll)
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(push ff ll))))
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ll))
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;;; org-sudoku ends here
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