PHP如何实现数独求解？本文主要介绍了PHP实现的数独求解问题，涉及php数组与字符串的遍历、比较、判断、运算等相关操作技巧，需要的朋友可以参考下。希望对大家有所帮助。

具体如下：

一、数独问题描述：

对于给出的数字二维数组，要求每行每列的数字不能重复。

二、实现代码：<?php

/* 数独求解程序

*

*/

class Sudoku {

var $matrix;

function __construct($arr = null) {

if ($arr == null) {

$this->clear();

} else {

$this->matrix = $arr;

}

}

function clear() {

for($i=0; $i<9; $i++) {

for($j=0; $j<9; $j++) {

$this->matrix[$i][$j] = array();

for ($k = 1; $k <= 9; $k++) {

$this->matrix[$i][$j][$k] = $k;

}

}

}

}

function setCell($row, $col, $value){

$this->matrix[$row][$col] = array($value => $value);

//row

for($i = 0; $i < 9; $i++){

if($i != $col){

if(! $this->removeValue($row, $i, $value)) {

return false;

}

}

}

//col

for($i = 0; $i < 9; $i++){

if($i != $row){

if(! $this->removeValue($i, $col, $value)) {

return false;

}

}

}

//square

$rs=intval($row / 3) * 3;

$cs=intval($col / 3) * 3;

for($i = $rs; $i < $rs + 3; $i++){

for($j = $cs; $j < $cs + 3; $j++){

if($i != $row && $j != $col){

if(! $this->removeValue($i, $j, $value))

return false;

}

}

}

return true;

}

function removeValue($row, $col, $value) {

$count = count($this->matrix[$row][$col]);

if($count == 1){

$ret = !isset($this->matrix[$row][$col][$value]);

return $ret;

}

if (isset($this->matrix[$row][$col][$value])) {

unset($this->matrix[$row][$col][$value]);

if($count - 1 == 1) {

return $this->setCell($row, $col, current($this->matrix[$row][$col]));

}

}

return true;

}

function set($arr) {

for ($i = 0; $i < 9; $i++) {

for ($j = 0; $j < 9; $j++) {

if ($arr[$i][$j] > 0) {

$this->setCell($i, $j, $arr[$i][$j]);

}

}

}

}

function dump() {

for($i = 0; $i < 9; $i++){

for($j = 0; $j < 9; $j++){

$c = count($this->matrix[$i][$j]);

if($c == 1){

echo " ".current($this->matrix[$i][$j])." ";

} else {

echo "(".$c.")";

}

}

echo "\n";

}

echo "\n";

}

function dumpAll() {

for($i = 0; $i < 9; $i++){

for($j = 0; $j < 9; $j++){

echo implode('', $this->matrix[$i][$j]), "\t";

}

echo "\n";

}

echo "\n";

}

function calc($data) {

$this->clear();

$this->set($data);

$this->_calc();

$this->dump();

}

function _calc() {

for($i = 0; $i < 9; $i++){

for($j = 0; $j < 9; $j++){

if(count($this->matrix[$i][$j]) == 1) {

continue;

}

foreach($this->matrix[$i][$j] as $v){

$flag = false;

$t = new Sudoku($this->matrix);

if(!$t->setCell($i, $j, $v)){

continue;

}

if(!$t->_calc()){

continue;

}

$this->matrix = $t->matrix;

return true;

}

return false;

}

}

return true;

}

}

$sd=new Sudoku;

$sd->calc(array(

array(0,5,0,0,0,6,0,9,0),

array(0,4,7,0,8,2,6,0,0),

array(0,8,0,0,0,7,0,5,2),

array(7,0,1,0,3,4,0,0,6),

array(0,3,0,0,2,0,0,8,0),

array(2,0,0,0,0,1,9,0,4),

array(4,7,0,1,0,0,0,6,0),

array(0,0,9,4,6,0,3,7,0),

array(0,1,0,2,0,0,0,4,0),

));

$sd->calc(array(

array(1,0,0,0,0,6,9,0,0),

array(0,0,0,9,0,0,0,0,5),

array(2,0,0,1,0,0,0,0,3),

array(0,0,5,3,0,7,0,2,0),

array(3,0,0,6,0,0,0,0,1),

array(0,1,0,4,0,0,8,0,0),

array(9,0,0,0,0,2,0,0,7),

array(5,0,0,0,0,9,0,0,0),

array(0,0,3,7,0,0,0,0,4),

));

$sd->calc(array(

array(7,0,0,1,0,0,0,0,5),

array(0,0,6,0,4,0,0,8,0),

array(0,0,1,0,0,0,0,0,0),

array(0,6,0,0,8,0,0,0,3),

array(0,8,0,0,0,9,0,7,0),

array(1,0,0,0,0,0,0,5,0),

array(0,0,0,0,0,0,9,0,0),

array(0,4,0,0,3,0,1,0,0),

array(9,0,0,0,0,7,0,0,2),

));

$sd->calc(array(

array(0,5,0,0,0,0,0,2,0),

array(0,0,3,1,0,0,5,0,0),

array(0,0,6,0,0,8,0,0,0),

array(6,0,0,0,0,0,0,1,0),

array(8,0,0,6,0,0,0,0,4),

array(0,3,0,0,0,9,0,0,7),

array(0,0,0,5,0,0,3,0,0),

array(0,0,8,0,0,6,9,0,0),

array(0,9,0,0,0,0,0,7,0),

));

?>

运行结果如下：1 5 2 3 4 6 7 9 8

9 4 7 5 8 2 6 1 3

3 8 6 9 1 7 4 5 2

7 9 1 8 3 4 5 2 6

5 3 4 6 2 9 1 8 7

2 6 8 7 5 1 9 3 4

4 7 3 1 9 8 2 6 5

8 2 9 4 6 5 3 7 1

6 1 5 2 7 3 8 4 9

1 3 7 2 5 6 9 4 8

4 6 8 9 7 3 2 1 5

2 5 9 1 8 4 6 7 3

6 8 5 3 1 7 4 2 9

3 9 4 6 2 8 7 5 1

7 1 2 4 9 5 8 3 6

9 4 6 5 3 2 1 8 7

5 7 1 8 4 9 3 6 2

8 2 3 7 6 1 5 9 4

7 3 8 1 9 6 4 2 5

2 9 6 3 4 5 7 8 1

4 5 1 2 7 8 3 9 6

5 6 9 7 8 4 2 1 3

3 8 2 5 1 9 6 7 4

1 7 4 6 2 3 8 5 9

6 2 7 4 5 1 9 3 8

8 4 5 9 3 2 1 6 7

9 1 3 8 6 7 5 4 2

9 5 1 3 6 7 4 2 8

7 8 3 1 4 2 5 6 9

2 4 6 9 5 8 7 3 1

6 2 9 4 7 5 8 1 3

8 7 5 6 1 3 2 9 4

1 3 4 2 8 9 6 5 7

4 6 7 5 9 1 3 8 2

3 1 8 7 2 6 9 4 5

5 9 2 8 3 4 1 7 6

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