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Initial data commit

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Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 72d218235f
commit f23f22d71c
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73
Task/N-queens-problem/PHP/n-queens-problem-2.php Normal file
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<html>
<body>
<pre>
<?php
/*************************************************************************
*
* This algorithm solves the 8 queens problem using backtracking.
* Please try with N<=25 * * * *************************************************************************/
class Queens {
var $size;
var $arr;
var $sol;
function Queens($n = 8) {
$this->size = $n;
$this->arr = array();
$this->sol = 0;
// Inicialiate array;
for($i=0; $i<$n; $i++) {
$this->arr[$i] = 0;
}
}
function isSolution($n) {
for ($i = 0; $i < $n; $i++) {
if ($this->arr[$i] == $this->arr[$n] ||
($this->arr[$i] - $this->arr[$n]) == ($n - $i) ||
($this->arr[$n] - $this->arr[$i]) == ($n - $i))
{
return false;
}
}
return true;
}
function PrintQueens() {
echo("solution #".(++$this->sol)."\n");
// echo("solution #".($this->size)."\n");
for ($i = 0; $i < $this->size; $i++) {
for ($j = 0; $j < $this->size; $j++) {
if ($this->arr[$i] == $j) echo("& ");
else echo(". ");
}
echo("\n");
}
echo("\n");
}
// backtracking Algorithm
function run($n = 0) {
if ($n == $this->size){
$this->PrintQueens();
}
else {
for ($i = 0; $i < $this->size; $i++) {
$this->arr[$n] = $i;
if($this->isSolution($n)){
$this->run($n+1);
}
}
}
}
}
$myprogram = new Queens(8);
$myprogram->run();
?>
</pre>
</body>
</html>