PHP - 2.580.210 Hinweise
Dadurch werden zuerst die letzte Zeile und Spalte sowie die rechte untere Ecke aller Kästchen entfernt. Anschließend wird versucht, jede Zelle zu löschen und die Karte nach jeder Änderung einem einfachen Solver zu unterziehen, um sicherzustellen, dass die Karte immer noch eindeutig lösbar ist.
Ein Großteil des folgenden Codes wurde von einer meiner alten Antworten geändert . printBoardverwendet 0s für leere Zellen.
<?php
// checks each row/col/block and removes impossible candidates
function reduce($cand){
do{
$old = $cand;
for($r = 0; $r < 9; ++$r){
for($c = 0; $c < 9; ++$c){
if(count($cand[$r][$c]) == 1){ // if filled in
// remove values from row and col and block
$remove = $cand[$r][$c];
for($i = 0; $i < 9; ++$i){
$cand[$r][$i] = array_diff($cand[$r][$i],$remove);
$cand[$i][$c] = array_diff($cand[$i][$c],$remove);
$br = floor($r/3)*3+$i/3;
$bc = floor($c/3)*3+$i%3;
$cand[$br][$bc] = array_diff($cand[$br][$bc],$remove);
}
$cand[$r][$c] = $remove;
}
}}
}while($old != $cand);
return $cand;
}
// checks candidate list for completion
function done($cand){
for($r = 0; $r < 9; ++$r){
for($c = 0; $c < 9; ++$c){
if(count($cand[$r][$c]) != 1)
return false;
}}
return true;
}
// board format: [[1,2,0,3,..],[..],..], $b[$row][$col]
function solve($board){
$cand = [[],[],[],[],[],[],[],[],[]];
for($r = 0; $r < 9; ++$r){
for($c = 0; $c < 9; ++$c){
if($board[$r][$c]){ // if filled in
$cand[$r][$c] = [$board[$r][$c]];
}else{
$cand[$r][$c] = range(1, 9);
}
}}
$cand = reduce($cand);
if(done($cand)) // goto not really necessary
goto end; // but it feels good to use it
else return false;
end:
// back to board format
$b = [];
for($r = 0; $r < 9; ++$r){
$b[$r] = [];
for($c = 0; $c < 9; ++$c){
if(count($cand[$r][$c]) == 1)
$b[$r][$c] = array_pop($cand[$r][$c]);
else
$b[$r][$c] = 0;
}
}
return $b;
}
function add_zeros($board, $ind){
for($r = 0; $r < 9; ++$r){
for($c = 0; $c < 9; ++$c){
$R = ($r + (int)($ind/9)) % 9;
$C = ($c + (int)($ind%9)) % 9;
if($board[$R][$C]){
$tmp = $board[$R][$C];
$board[$R][$C] = 0;
if(!solve($board))
$board[$R][$C] = $tmp;
}
}}
return $board;
}
function generate($board, $ind){
// remove last row+col
$board[8] = [0,0,0,0,0,0,0,0,0];
foreach($board as &$j) $j[8] = 0;
// remove bottom corner of each box
$board[2][2] = $board[2][5] = $board[5][2] = $board[5][5] = 0;
$board = add_zeros($board, $ind);
return $board;
}
function countClues($board){
$str = implode(array_map('implode', $board));
return 81 - substr_count($str, '0');
}
function generateBoard($board){
return generate($board, 0);
}
function printBoard($board){
for($i = 0; $i < 9; ++$i){
echo implode(' ', $board[$i]) . PHP_EOL;
}
flush();
}
function readBoard($str){
$tmp = str_split($str, 9);
$board = [];
for($i = 0; $i < 9; ++$i)
$board[] = str_split($tmp[$i], 1);
return $board;
}
// testing
$n = 0;
$f = fopen('ppcg_sudoku_testing.txt', 'r');
while(($l = fgets($f)) !== false){
$board = readBoard(trim($l));
$n += countClues(generateBoard($board));
}
echo $n;