├── .gitignore ├── examples ├── hard-5.txt ├── hard-6.txt ├── hard-2.txt ├── hard-3.txt ├── hard-4.txt ├── medium-3.txt ├── hard-1.txt ├── hard-7.txt ├── medium-1.txt ├── medium-2.txt ├── simple-1.txt ├── simple-2.txt ├── simple-3.txt ├── medium-4.txt └── simple-4.txt ├── bin └── sudoku-solver.php ├── README.rst ├── src ├── Verifier.php ├── Sudoku.php └── Solver.php └── LICENSE /.gitignore: -------------------------------------------------------------------------------- 1 | README.html 2 | -------------------------------------------------------------------------------- /examples/hard-5.txt: -------------------------------------------------------------------------------- 1 | 7 5 3 2 | 946 3 | 5 82 4 | 3 5 5 | 3 1 2 6 | 8 7 7 | 56 7 8 | 591 9 | 2 4 8 10 | -------------------------------------------------------------------------------- /examples/hard-6.txt: -------------------------------------------------------------------------------- 1 | 68 2 | 73 9 3 | 3 9 45 4 | 49 5 | 8 3 5 9 2 6 | 36 7 | 96 3 8 8 | 7 68 9 | 28 10 | -------------------------------------------------------------------------------- /examples/hard-2.txt: -------------------------------------------------------------------------------- 1 | 2 4 8 2 | 5 43 3 | 49 1 4 | 1 5 5 | 4 8 7 6 | 8 3 7 | 5 79 8 | 13 2 9 | 9 6 2 10 | -------------------------------------------------------------------------------- /examples/hard-3.txt: -------------------------------------------------------------------------------- 1 | 719 6 2 | 61 4 3 | 2 3 4 | 7 3 5 | 432 6 | 9 5 7 | 7 8 8 | 3 19 9 | 4 769 10 | -------------------------------------------------------------------------------- /examples/hard-4.txt: -------------------------------------------------------------------------------- 1 | 4 3 2 | 2 14 3 | 71 2 4 | 2 9 4 5 | 3 5 8 6 | 6 2 7 7 | 6 97 8 | 69 5 9 | 1 8 10 | -------------------------------------------------------------------------------- /examples/medium-3.txt: -------------------------------------------------------------------------------- 1 | 2 5 81 2 | 4 21 3 | 13 5 4 | 97 1 5 | 3 4 5 6 | 2 87 7 | 2 59 8 | 65 1 9 | 87 6 3 10 | -------------------------------------------------------------------------------- /examples/hard-1.txt: -------------------------------------------------------------------------------- 1 | 3 42 2 | 1 9 3 | 3 6 7 4 | 1 5 8 5 | 7 1 3 6 | 4 8 6 7 | 3 9 8 8 | 2 6 9 | 87 5 10 | -------------------------------------------------------------------------------- /examples/hard-7.txt: -------------------------------------------------------------------------------- 1 | 8 31 4 2 | 4 8 3 | 3 24 6 9 4 | 124 5 | 8 7 6 | 857 7 | 1 7 59 4 8 | 7 6 9 | 2 41 8 10 | -------------------------------------------------------------------------------- /examples/medium-1.txt: -------------------------------------------------------------------------------- 1 | 4 237 2 | 65 2 3 | 29 5 4 | 7 3 58 5 | 2 6 | 35 1 2 7 | 2 15 8 | 7 93 9 | 453 6 10 | -------------------------------------------------------------------------------- /examples/medium-2.txt: -------------------------------------------------------------------------------- 1 | 6 4 7 2 | 9 6 51 3 | 98 6 4 | 3 6 4 5 | 5 1 3 6 | 4 8 9 7 | 9 42 8 | 28 1 3 9 | 6 1 7 10 | -------------------------------------------------------------------------------- /examples/simple-1.txt: -------------------------------------------------------------------------------- 1 | 3 9 2 | 28 57 3 | 86 4 4 | 83 479 5 5 | 2 1 8 6 | 9 683 41 7 | 1 42 8 | 67 82 9 | 1 3 10 | -------------------------------------------------------------------------------- /examples/simple-2.txt: -------------------------------------------------------------------------------- 1 | 9 81 5 2 | 7 9 2 3 | 2 37 4 | 53 1 6 9 5 | 6 2 3 6 | 8 3 9 62 7 | 73 2 8 | 8 5 7 9 | 4 16 9 10 | -------------------------------------------------------------------------------- /examples/simple-3.txt: -------------------------------------------------------------------------------- 1 | 35 74 2 | 26 9 71 3 | 7 142 3 4 | 3 2 5 | 8 6 | 6 5 7 | 4 567 2 8 | 15 7 86 9 | 92 35 10 | -------------------------------------------------------------------------------- /examples/medium-4.txt: -------------------------------------------------------------------------------- 1 | 8 57 2 | 6 83 9 3 | 4 37 4 | 14 6 5 | 5 2 1 6 | 9 84 7 | 38 2 8 | 7 95 4 9 | 82 6 10 | 11 | -------------------------------------------------------------------------------- /examples/simple-4.txt: -------------------------------------------------------------------------------- 1 | 1 4 2 | 8 54 97 3 | 28 5 4 | 3 48 7 5 | 2 9 5 6 8 6 | 7 62 9 7 | 2 63 8 | 67 42 5 9 | 1 7 10 | -------------------------------------------------------------------------------- /bin/sudoku-solver.php: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env php 2 | = 2) { 9 | $file = $argv[1]; 10 | } else { 11 | $file = __DIR__ . '/../examples/simple-2.txt'; 12 | } 13 | $input = file_get_contents($file); 14 | 15 | $data = array_fill(0, 9, array_fill(0, 9, '')); 16 | foreach (explode("\n", $input) as $lnum => $line) { 17 | $lparts = str_split(rtrim($line), 1); 18 | foreach ($lparts as $cnum => $c) { 19 | if (is_numeric($c)) { 20 | $data[$lnum][$cnum] = (int) $c; 21 | } 22 | } 23 | } 24 | 25 | $sd = new Sudoku(); 26 | $sd->data = $data; 27 | 28 | $solver = new Solver(); 29 | $solver->solve($sd); 30 | 31 | echo $sd; 32 | 33 | $verifier = new Verifier(); 34 | try { 35 | $verifier->verify($sd); 36 | echo "✔ solved\n"; 37 | exit(0); 38 | } catch (Exception $e) { 39 | echo "✘ not solved: " . $e->getMessage() . "\n"; 40 | exit(1); 41 | } 42 | ?> 43 | -------------------------------------------------------------------------------- /README.rst: -------------------------------------------------------------------------------- 1 | ************* 2 | Sudoku solver 3 | ************* 4 | A tool that solves sudoku puzzles. 5 | Solves easy and hard puzzles. 6 | 7 | It uses two approaches to solve a sudoku: 8 | 9 | 1. Create an index with all possible values of a cell. 10 | Whenever a cell's number is determined, remove this value from the 11 | possibilities of all cells in the same row, same column and same 3x3 square. 12 | Once only one possible value is left for a cell, use that. 13 | Repeat. 14 | 2. In addition to point 1, calculate the following for each of the possible values: 15 | Check if the possible value is allowed in other cells in the same row - if 16 | not, use it. Do the same for the same column and the same 3x3 square. 17 | 18 | 19 | Usage 20 | ===== 21 | Write the sudoku into a text file:: 22 | 23 | 7 5 3 24 | 946 25 | 5 82 26 | 3 5 27 | 3 1 2 28 | 8 7 29 | 56 7 30 | 591 31 | 2 4 8 32 | 33 | Run the solver with the file name:: 34 | 35 | $ ./bin/sudoku-solver.php examples/hard-5.txt 36 | ╔═══╤═══╤═══╗ 37 | ║7 │ 5│ 3║ 38 | ║946│ │ ║ 39 | ║ 5 │82 │ ║ 40 | ╟───┼───┼───╢ 41 | ║ │ 3│ 5 ║ 42 | ║ 3│ 1 │2 ║ 43 | ║ 8 │7 │ ║ 44 | ╟───┼───┼───╢ 45 | ║ │ 56│ 7 ║ 46 | ║ │ │591║ 47 | ║2 │4 │ 8║ 48 | ╚═══╧═══╧═══╝ 49 | 50 | ╔═══╤═══╤═══╗ 51 | ║728│645│913║ 52 | ║946│371│825║ 53 | ║351│829│746║ 54 | ╟───┼───┼───╢ 55 | ║172│983│654║ 56 | ║693│514│287║ 57 | ║584│762│139║ 58 | ╟───┼───┼───╢ 59 | ║839│156│472║ 60 | ║467│238│591║ 61 | ║215│497│368║ 62 | ╚═══╧═══╧═══╝ 63 | ✔ solved 64 | 65 | 66 | Dependencies 67 | ============ 68 | PHP 5.4+ 69 | 70 | 71 | Author 72 | ====== 73 | Christian Weiske, cweiske+sudoku-solver@cweiske.de 74 | 75 | 76 | License 77 | ======= 78 | AGPLv3 or later 79 | -------------------------------------------------------------------------------- /src/Verifier.php: -------------------------------------------------------------------------------- 1 | data[$row][$col] != '') { 10 | ++$values; 11 | } 12 | } 13 | } 14 | if ($values < 81) { 15 | throw new Exception( 16 | 'Not fully filled - ' . $values . '/81' 17 | ); 18 | } 19 | 20 | //rows 21 | foreach ($sd->data as $lnum => $arLine) { 22 | $sum = array_sum($arLine); 23 | if ($sum != 45) { 24 | throw new Exception( 25 | 'Sum of line ' . $lnum . ' is not 45 but ' . $sum 26 | ); 27 | } 28 | } 29 | 30 | //cols 31 | for ($n = 0; $n < 9; $n++) { 32 | $sum = array_sum(array_column($sd->data, $n)); 33 | if ($sum != 45) { 34 | throw new Exception( 35 | 'Sum of column ' . $lnum . ' is not 45 but ' . $sum 36 | ); 37 | } 38 | } 39 | 40 | //squares 41 | $squares = array( 42 | array(0, 0), array(0, 3), array(0, 6), 43 | array(3, 0), array(3, 3), array(3, 6), 44 | array(6, 0), array(6, 3), array(6, 6), 45 | ); 46 | foreach ($squares as $sqpos) { 47 | list($row, $col) = $sqpos; 48 | $sum = 0; 49 | for ($nr = $row; $nr < $row + 3; $nr++) { 50 | for ($nc = $col; $nc < $col + 3; $nc++) { 51 | $sum += $sd->data[$nr][$nc]; 52 | } 53 | } 54 | if ($sum != 45) { 55 | throw new Exception( 56 | 'Sum of square ' . $row . ',' . $col 57 | . ' is not 45 but ' . $sum 58 | ); 59 | } 60 | } 61 | } 62 | } 63 | ?> 64 | -------------------------------------------------------------------------------- /src/Sudoku.php: -------------------------------------------------------------------------------- 1 | renderMinimal(); 9 | //return $this->renderSmall(); 10 | return $this->renderPretty(); 11 | } 12 | 13 | public function renderPretty() 14 | { 15 | $str = ''; 16 | $str .= "╔═══╤═══╤═══╗\n"; 17 | foreach ($this->data as $row => $arLine) { 18 | if ($row > 0 && $row % 3 == 0) { 19 | $str .= "╟───┼───┼───╢\n"; 20 | } 21 | $str .= '║'; 22 | foreach ($arLine as $col => $val) { 23 | if ($col > 0 && $col % 3 == 0) { 24 | $str .= '│'; 25 | } 26 | if (is_int($val)) { 27 | $str .= $val; 28 | } else { 29 | $str .= ' '; 30 | } 31 | } 32 | $str .= "║\n"; 33 | } 34 | $str .= "╚═══╧═══╧═══╝\n"; 35 | return $str; 36 | } 37 | 38 | public function renderSmall() 39 | { 40 | $str = ''; 41 | foreach ($this->data as $row => $arLine) { 42 | if ($row > 0 && $row % 3 == 0) { 43 | $str .= "---+---+---\n"; 44 | } 45 | foreach ($arLine as $col => $val) { 46 | if ($col > 0 && $col % 3 == 0) { 47 | $str .= '|'; 48 | } 49 | if (is_int($val)) { 50 | $str .= $val; 51 | } else { 52 | $str .= ' '; 53 | } 54 | } 55 | $str .= "\n"; 56 | } 57 | return $str; 58 | } 59 | 60 | public function renderMinimal() 61 | { 62 | $str = ''; 63 | foreach ($this->data as $lnum => $arLine) { 64 | foreach ($arLine as $cnum => $val) { 65 | if (is_int($val)) { 66 | $str .= $val; 67 | } else { 68 | $str .= ' '; 69 | } 70 | } 71 | $str .= "\n"; 72 | } 73 | return $str; 74 | } 75 | } 76 | ?> 77 | -------------------------------------------------------------------------------- /src/Solver.php: -------------------------------------------------------------------------------- 1 | sd = $sd; 11 | $this->possibilities = array_fill( 12 | 0, 9, 13 | array_fill( 14 | 0, 9, 15 | array_combine(range(1, 9), range(1, 9)) 16 | ) 17 | ); 18 | 19 | $arValueCoords = $this->getCellsWithValues(); 20 | foreach ($arValueCoords as $arCoords) { 21 | list($row, $col) = $arCoords; 22 | $this->possibilities[$row][$col] = array(); 23 | } 24 | foreach ($arValueCoords as $arCoords) { 25 | list($row, $col) = $arCoords; 26 | $this->reducePossibilities($row, $col); 27 | } 28 | echo $sd . "\n"; 29 | 30 | do { 31 | $bChanged = false; 32 | do { 33 | //echo "--calc single\n"; 34 | $nReduced = $this->calculateSingles(); 35 | //$nReduced = 0; 36 | if ($nReduced > 0) { 37 | $bChanged = true; 38 | //echo $sd . "\n"; 39 | } 40 | } while ($nReduced > 0); 41 | 42 | do { 43 | //echo "--calc excl\n"; 44 | $nReduced = $this->calculateExclusions(); 45 | if ($nReduced > 0) { 46 | $bChanged = true; 47 | //echo $sd . "\n"; 48 | } 49 | } while ($nReduced > 0); 50 | } while ($bChanged); 51 | } 52 | 53 | public function calculateSingles() 54 | { 55 | $nReduced = 0; 56 | $arSingleCoords = $this->getSinglePossibilityCoords(); 57 | foreach ($arSingleCoords as $arCoords) { 58 | list($row, $col) = $arCoords; 59 | $val = reset($this->possibilities[$row][$col]); 60 | $nReduced += $this->setValue($row, $col, $val); 61 | } 62 | return $nReduced; 63 | } 64 | 65 | public function reducePossibilities($row, $col) 66 | { 67 | $nReduced = 0; 68 | $val = $this->sd->data[$row][$col]; 69 | 70 | //all in that row 71 | foreach ($this->possibilities[$row] as $pCol => &$arPoss) { 72 | if (isset($arPoss[$val])) { 73 | unset($arPoss[$val]); 74 | ++$nReduced; 75 | } 76 | } 77 | 78 | //all in that col 79 | for ($pRow = 0; $pRow < 9; $pRow++) { 80 | if (isset($this->possibilities[$pRow][$col][$val])) { 81 | unset($this->possibilities[$pRow][$col][$val]); 82 | ++$nReduced; 83 | } 84 | } 85 | 86 | //all in that square 87 | foreach ($this->getSquareCoords($row, $col) as $arCoords) { 88 | list($pRow, $pCol) = $arCoords; 89 | if (isset($this->possibilities[$pRow][$pCol][$val])) { 90 | unset($this->possibilities[$pRow][$pCol][$val]); 91 | ++$nReduced; 92 | } 93 | } 94 | return $nReduced; 95 | } 96 | 97 | public function calculateExclusions() 98 | { 99 | // calculate numbers only possible in one place in a row/col/square 100 | $nReduced = 0; 101 | 102 | //1. rows 103 | for ($row = 0; $row < 9; $row++) { 104 | $arNumbers = array(); 105 | for ($col = 0; $col < 9; $col++) { 106 | if ($this->sd->data[$row][$col] != '') { 107 | continue; 108 | } 109 | foreach ($this->possibilities[$row][$col] as $val) { 110 | $arNumbers[$val][] = array($row, $col); 111 | } 112 | } 113 | foreach ($arNumbers as $val => $arValues) { 114 | if (count($arValues) == 1) { 115 | list($row, $col) = reset($arValues); 116 | $nReduced += $this->setValue($row, $col, $val); 117 | } 118 | } 119 | } 120 | 121 | //2. cols 122 | for ($col = 0; $col < 9; $col++) { 123 | $arNumbers = array(); 124 | for ($row = 0; $row < 9; $row++) { 125 | if ($this->sd->data[$row][$col] != '') { 126 | continue; 127 | } 128 | foreach ($this->possibilities[$row][$col] as $val) { 129 | $arNumbers[$val][] = array($row, $col); 130 | } 131 | } 132 | foreach ($arNumbers as $val => $arValues) { 133 | if (count($arValues) == 1) { 134 | list($row, $col) = reset($arValues); 135 | $nReduced += $this->setValue($row, $col, $val); 136 | } 137 | } 138 | } 139 | 140 | //3. squares 141 | foreach ($this->getSquareRoots() as $arSquareRootCoords) { 142 | list($rRow, $rCol) = $arSquareRootCoords; 143 | $arNumbers = array(); 144 | foreach ($this->getSquareCoords($rRow, $rCol) as $arCoords) { 145 | list($row, $col) = $arCoords; 146 | if ($this->sd->data[$row][$col] != '') { 147 | continue; 148 | } 149 | foreach ($this->possibilities[$row][$col] as $val) { 150 | $arNumbers[$val][] = array($row, $col); 151 | } 152 | } 153 | foreach ($arNumbers as $val => $arValues) { 154 | if (count($arValues) == 1) { 155 | list($row, $col) = reset($arValues); 156 | $nReduced += $this->setValue($row, $col, $val); 157 | } 158 | } 159 | } 160 | 161 | return $nReduced; 162 | } 163 | 164 | public function getCellsWithValues() 165 | { 166 | $arValueCoords = array(); 167 | for ($row = 0; $row < 9; $row++) { 168 | for ($col = 0; $col < 9; $col++) { 169 | if ($this->sd->data[$row][$col] != '') { 170 | $arValueCoords[] = array($row, $col); 171 | } 172 | } 173 | } 174 | return $arValueCoords; 175 | } 176 | 177 | public function getSinglePossibilityCoords() 178 | { 179 | $arCoords = array(); 180 | for ($row = 0; $row < 9; $row++) { 181 | for ($col = 0; $col < 9; $col++) { 182 | if (count($this->possibilities[$row][$col]) == 1) { 183 | $arCoords[] = array($row, $col); 184 | } 185 | } 186 | } 187 | return $arCoords; 188 | } 189 | 190 | public function getSquareCoords($row, $col) 191 | { 192 | $sRow = $row - $row % 3; 193 | $sCol = $col - $col % 3; 194 | 195 | return array( 196 | array($sRow + 0, $sCol + 0), 197 | array($sRow + 0, $sCol + 1), 198 | array($sRow + 0, $sCol + 2), 199 | array($sRow + 1, $sCol + 0), 200 | array($sRow + 1, $sCol + 1), 201 | array($sRow + 1, $sCol + 2), 202 | array($sRow + 2, $sCol + 0), 203 | array($sRow + 2, $sCol + 1), 204 | array($sRow + 2, $sCol + 2), 205 | ); 206 | } 207 | 208 | public function getSquareRoots() 209 | { 210 | return array( 211 | array(0, 0), array(0, 3), array(0, 6), 212 | array(3, 0), array(3, 3), array(3, 6), 213 | array(6, 0), array(6, 3), array(6, 6), 214 | ); 215 | } 216 | 217 | public function setValue($row, $col, $val) 218 | { 219 | if ($this->sd->data[$row][$col] != '') { 220 | throw new Exception( 221 | 'Trying to overwrite existing value: ' 222 | . $row . ',' . $col 223 | . ' - ' . $this->sd->data[$row][$col] 224 | . ' with ' . $val 225 | ); 226 | } 227 | $this->sd->data[$row][$col] = $val; 228 | $this->possibilities[$row][$col] = array(); 229 | return $this->reducePossibilities($row, $col); 230 | } 231 | } 232 | ?> 233 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU AFFERO GENERAL PUBLIC LICENSE 2 | Version 3, 19 November 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU Affero General Public License is a free, copyleft license for 11 | software and other kinds of works, specifically designed to ensure 12 | cooperation with the community in the case of network server software. 13 | 14 | The licenses for most software and other practical works are designed 15 | to take away your freedom to share and change the works. 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Patents. 460 | 461 | A "contributor" is a copyright holder who authorizes use under this 462 | License of the Program or a work on which the Program is based. The 463 | work thus licensed is called the contributor's "contributor version". 464 | 465 | A contributor's "essential patent claims" are all patent claims 466 | owned or controlled by the contributor, whether already acquired or 467 | hereafter acquired, that would be infringed by some manner, permitted 468 | by this License, of making, using, or selling its contributor version, 469 | but do not include claims that would be infringed only as a 470 | consequence of further modification of the contributor version. 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You may not convey a covered 513 | work if you are a party to an arrangement with a third party that is 514 | in the business of distributing software, under which you make payment 515 | to the third party based on the extent of your activity of conveying 516 | the work, and under which the third party grants, to any of the 517 | parties who would receive the covered work from you, a discriminatory 518 | patent license (a) in connection with copies of the covered work 519 | conveyed by you (or copies made from those copies), or (b) primarily 520 | for and in connection with specific products or compilations that 521 | contain the covered work, unless you entered into that arrangement, 522 | or that patent license was granted, prior to 28 March 2007. 523 | 524 | Nothing in this License shall be construed as excluding or limiting 525 | any implied license or other defenses to infringement that may 526 | otherwise be available to you under applicable patent law. 527 | 528 | 12. 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Remote Network Interaction; Use with the GNU General Public License. 541 | 542 | Notwithstanding any other provision of this License, if you modify the 543 | Program, your modified version must prominently offer all users 544 | interacting with it remotely through a computer network (if your version 545 | supports such interaction) an opportunity to receive the Corresponding 546 | Source of your version by providing access to the Corresponding Source 547 | from a network server at no charge, through some standard or customary 548 | means of facilitating copying of software. This Corresponding Source 549 | shall include the Corresponding Source for any work covered by version 3 550 | of the GNU General Public License that is incorporated pursuant to the 551 | following paragraph. 552 | 553 | Notwithstanding any other provision of this License, you have 554 | permission to link or combine any covered work with a work licensed 555 | under version 3 of the GNU General Public License into a single 556 | combined work, and to convey the resulting work. The terms of this 557 | License will continue to apply to the part which is the covered work, 558 | but the work with which it is combined will remain governed by version 559 | 3 of the GNU General Public License. 560 | 561 | 14. Revised Versions of this License. 562 | 563 | The Free Software Foundation may publish revised and/or new versions of 564 | the GNU Affero General Public License from time to time. Such new versions 565 | will be similar in spirit to the present version, but may differ in detail to 566 | address new problems or concerns. 567 | 568 | Each version is given a distinguishing version number. If the 569 | Program specifies that a certain numbered version of the GNU Affero General 570 | Public License "or any later version" applies to it, you have the 571 | option of following the terms and conditions either of that numbered 572 | version or of any later version published by the Free Software 573 | Foundation. If the Program does not specify a version number of the 574 | GNU Affero General Public License, you may choose any version ever published 575 | by the Free Software Foundation. 576 | 577 | If the Program specifies that a proxy can decide which future 578 | versions of the GNU Affero General Public License can be used, that proxy's 579 | public statement of acceptance of a version permanently authorizes you 580 | to choose that version for the Program. 581 | 582 | Later license versions may give you additional or different 583 | permissions. However, no additional obligations are imposed on any 584 | author or copyright holder as a result of your choosing to follow a 585 | later version. 586 | 587 | 15. Disclaimer of Warranty. 588 | 589 | THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY 590 | APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT 591 | HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY 592 | OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, 593 | THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 594 | PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM 595 | IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF 596 | ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 597 | 598 | 16. Limitation of Liability. 599 | 600 | IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING 601 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS 602 | THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY 603 | GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE 604 | USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF 605 | DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD 606 | PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), 607 | EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF 608 | SUCH DAMAGES. 609 | 610 | 17. Interpretation of Sections 15 and 16. 611 | 612 | If the disclaimer of warranty and limitation of liability provided 613 | above cannot be given local legal effect according to their terms, 614 | reviewing courts shall apply local law that most closely approximates 615 | an absolute waiver of all civil liability in connection with the 616 | Program, unless a warranty or assumption of liability accompanies a 617 | copy of the Program in return for a fee. 618 | 619 | END OF TERMS AND CONDITIONS 620 | 621 | How to Apply These Terms to Your New Programs 622 | 623 | If you develop a new program, and you want it to be of the greatest 624 | possible use to the public, the best way to achieve this is to make it 625 | free software which everyone can redistribute and change under these terms. 626 | 627 | To do so, attach the following notices to the program. It is safest 628 | to attach them to the start of each source file to most effectively 629 | state the exclusion of warranty; and each file should have at least 630 | the "copyright" line and a pointer to where the full notice is found. 631 | 632 | 633 | Copyright (C) 634 | 635 | This program is free software: you can redistribute it and/or modify 636 | it under the terms of the GNU Affero General Public License as published by 637 | the Free Software Foundation, either version 3 of the License, or 638 | (at your option) any later version. 639 | 640 | This program is distributed in the hope that it will be useful, 641 | but WITHOUT ANY WARRANTY; without even the implied warranty of 642 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 643 | GNU Affero General Public License for more details. 644 | 645 | You should have received a copy of the GNU Affero General Public License 646 | along with this program. If not, see . 647 | 648 | Also add information on how to contact you by electronic and paper mail. 649 | 650 | If your software can interact with users remotely through a computer 651 | network, you should also make sure that it provides a way for users to 652 | get its source. For example, if your program is a web application, its 653 | interface could display a "Source" link that leads users to an archive 654 | of the code. There are many ways you could offer source, and different 655 | solutions will be better for different programs; see section 13 for the 656 | specific requirements. 657 | 658 | You should also get your employer (if you work as a programmer) or school, 659 | if any, to sign a "copyright disclaimer" for the program, if necessary. 660 | For more information on this, and how to apply and follow the GNU AGPL, see 661 | . 662 | --------------------------------------------------------------------------------