79 lines
1.7 KiB
PHP
79 lines
1.7 KiB
PHP
<?php
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namespace alveolata\algorithm;
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require_once(DIR_ALVEOLATA . '/list/functions.php');
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/**
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* @param array $order {map<§x,list<§x>>}
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* @return array {list<§x>}
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* @throw \Exception if not possible
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*/
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function topsort(
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array $order
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) : array
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{
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if (empty($order)) {
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return [];
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}
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else {
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foreach ($order as $member => $dependencies) {
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if (count($dependencies) <= 0) {
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$order_ = [];
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foreach ($order as $member_ => $dependencies_) {
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if ($member === $member_) {
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// do nothing
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}
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else {
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$order_[$member_] = \alveolata\list_\filter/*<§x,bool>*/(
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$dependencies_,
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function ($dependency_) use ($member) : bool {
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return (! ($member === $dependency_));
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}
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);
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}
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}
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return array_merge([$member], topsort($order_));
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}
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}
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throw (new \Exception('not sortable'));
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}
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}
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/**
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* calculates the levenshtein distance between two strings
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*/
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function levenshtein(string $x, string $y) : int
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{
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$u = str_split($x);
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$v = str_split($y);
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// init
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$matrix = array_map(
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fn($i) => array_map(fn($j) => null, \alveolata\list_\sequence(count($u)+1)),
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\alveolata\list_\sequence(count($v)+1)
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);
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foreach (\alveolata\list_\sequence(count($u)+1) as $i) {$matrix[$i][0] = $i;}
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foreach (\alveolata\list_\sequence(count($v)+1) as $j) {$matrix[0][$j] = $j;}
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// feed
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foreach (\alveolata\list_\sequence(count($u)) as $i) {
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foreach (\alveolata\list_\sequence(count($v)) as $j) {
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$matrix[$i+1][$j+1] = min(
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min(
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($matrix[$i+1][$j+0] + 1),
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($matrix[$i+0][$j+1] + 1)
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),
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($matrix[$i+0][$j+0] + (($u[$i] === $v[$j]) ? 0 : 1))
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);
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}
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}
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// return
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return $matrix[count($u)][count($v)];
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}
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?>
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