Detailed explanation of how to solve Sudoku in PHP

How to solve Sudoku in PHP? This article mainly introduces the Sudoku solving problem implemented in PHP, involving the traversal, comparison, judgment, operation and other related operation skills of PHP arrays and strings. Friends in need can refer to it. I hope to be helpful.

The details are as follows:

1. Sudoku problem description:

For the given two-dimensional array of numbers, the numbers in each row and column are required Cannot be repeated.

2. Implementation code:

<?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(&#39;&#39;, $this->matrix[$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),
));
?>

The running results are as follows:

 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

Related recommendations:

Some introduction to PHP array functions

PHP array traversal foreach syntax structure and examples

php array processing function extract detailed explanation and example code

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