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mirahmanmirahman
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Restructured the code base
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‎Algorithms/Graph/BFS.php‎

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<?php
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/*
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* Author: Mizanur rahman <[email protected]>
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*
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*/
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function BFS(array &$graph, int $start, array $visited): SplQueue {
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$queue = new SplQueue;
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$path = new SplQueue;
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$queue->enqueue($start);
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$visited[$start] = 1;
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while (!$queue->isEmpty()) {
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$node = $queue->dequeue();
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$path->enqueue($node);
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foreach ($graph[$node] as $key => $vertex) {
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if (!$visited[$key] && $vertex == 1) {
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$visited[$key] = 1;
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$queue->enqueue($key);
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}
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}
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}
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return $path;
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}
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$graph = [
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0 => [0, 1, 1, 0, 0, 0],
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1 => [1, 0, 0, 1, 0, 0],
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2 => [1, 0, 0, 1, 0, 0],
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3 => [0, 1, 1, 0, 1, 0],
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4 => [0, 0, 0, 1, 0, 1],
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5 => [0, 0, 0, 0, 1, 0],
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];
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$graph = [];
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$visited = [];
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$vertexCount = 6;
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for ($i = 1; $i <= $vertexCount; $i++) {
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$graph[$i] = array_fill(1, $vertexCount, 0);
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$visited[$i] = 0;
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}
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$graph[1][2] = $graph[2][1] = 1;
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$graph[1][5] = $graph[5][1] = 1;
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$graph[5][2] = $graph[2][5] = 1;
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$graph[5][4] = $graph[4][5] = 1;
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$graph[4][3] = $graph[3][4] = 1;
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$graph[3][2] = $graph[2][3] = 1;
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$graph[6][4] = $graph[4][6] = 1;
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$path = BFS($graph, 5, $visited);
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while (!$path->isEmpty()) {
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echo $path->dequeue() . "\t";
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}
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‎Algorithms/Graph/BellmanFord.php‎

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<?php
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/*
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* Author: Mizanur rahman <[email protected]>
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*
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*/
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function bellmanFord(array $graph, int $source): array {
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$dist = [];
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$len = count($graph);
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foreach ($graph as $v => $adj) {
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$dist[$v] = PHP_INT_MAX;
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}
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$dist[$source] = 0;
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for ($k = 0; $k < $len - 1; $k++) {
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for ($i = 0; $i < $len; $i++) {
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for ($j = 0; $j < $len; $j++) {
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if ($dist[$i] > $dist[$j] + $graph[$j][$i]) {
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$dist[$i] = $dist[$j] + $graph[$j][$i];
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}
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}
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}
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}
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for ($i = 0; $i < $len; $i++) {
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for ($j = 0; $j < $len; $j++) {
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if ($dist[$i] > $dist[$j] + $graph[$j][$i]) {
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echo 'The graph contains a negative-weight cycle!';
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return [];
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}
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}
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}
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return $dist;
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}
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define("I", PHP_INT_MAX);
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$graph = [
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0 => [I, 3, 5, 9, I, I],
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1 => [3, I, 3, 4, 7, I],
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2 => [5, 3, I, 2, 6, 3],
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3 => [9, 4, 2, I, 2, 2],
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4 => [I, 7, 6, 2, I, 5],
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5 => [I, I, 3, 2, 5, I]
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];
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$matrix = array(
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0 => array(0, 3, 4),
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1 => array(0, 0, 2),
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2 => array(0, -2, 0),
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);
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$source = 0;
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$distances = bellmanFord($graph, $source);
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foreach($distances as $target => $distance) {
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echo "distance from $source to $target is $distance \n";
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}

‎Algorithms/Graph/DFS.php‎

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<?php
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/*
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* Author: Mizanur rahman <[email protected]>
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*
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*/
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function DFS(array &$graph, int $start, array $visited): SplQueue {
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$stack = new SplStack;
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$path = new SplQueue;
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$stack->push($start);
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$visited[$start] = 1;
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while (!$stack->isEmpty()) {
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$node = $stack->pop();
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$path->enqueue($node);
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foreach ($graph[$node] as $key => $vertex) {
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if (!$visited[$key] && $vertex == 1) {
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$visited[$key] = 1;
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$stack->push($key);
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}
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}
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}
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return $path;
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}
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$graph = [
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0 => [0, 1, 1, 0, 0, 0],
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1 => [1, 0, 0, 1, 0, 0],
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2 => [1, 0, 0, 1, 0, 0],
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3 => [0, 1, 1, 0, 1, 0],
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4 => [0, 0, 0, 1, 0, 1],
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5 => [0, 0, 0, 0, 1, 0],
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];
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$graph = [];
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$visited = [];
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$vertexCount = 6;
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for ($i = 1; $i <= $vertexCount; $i++) {
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$graph[$i] = array_fill(1, $vertexCount, 0);
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$visited[$i] = 0;
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}
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$graph[1][2] = $graph[2][1] = 1;
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$graph[1][5] = $graph[5][1] = 1;
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$graph[5][2] = $graph[2][5] = 1;
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$graph[5][4] = $graph[4][5] = 1;
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$graph[4][3] = $graph[3][4] = 1;
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$graph[3][2] = $graph[2][3] = 1;
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$graph[6][4] = $graph[4][6] = 1;
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$path = DFS($graph, 1, $visited);
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while (!$path->isEmpty()) {
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echo $path->dequeue() . "\t";
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}
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‎Algorithms/Graph/Dijkstra.php‎

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<?php
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/*
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* Author: Mizanur rahman <[email protected]>
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*
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*/
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function Dijkstra(array $graph, string $source, string $target): array {
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$dist = [];
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$pred = [];
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$Queue = new SplPriorityQueue();
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foreach ($graph as $v => $adj) {
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$dist[$v] = PHP_INT_MAX;
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$pred[$v] = null;
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$Queue->insert($v, min($adj));
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}
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$dist[$source] = 0;
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while (!$Queue->isEmpty()) {
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$u = $Queue->extract();
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if (!empty($graph[$u])) {
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foreach ($graph[$u] as $v => $cost) {
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if ($dist[$u] + $cost < $dist[$v]) {
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$dist[$v] = $dist[$u] + $cost;
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$pred[$v] = $u;
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}
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}
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}
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}
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$S = new SplStack();
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$u = $target;
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$distance = 0;
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while (isset($pred[$u]) && $pred[$u]) {
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$S->push($u);
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$distance += $graph[$u][$pred[$u]];
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$u = $pred[$u];
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}
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if ($S->isEmpty()) {
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return ["distance" => 0, "path" => $S];
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} else {
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$S->push($source);
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return ["distance" => $distance, "path" => $S];
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}
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}
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$graph = [
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'A' => ['B' => 3, 'C' => 5, 'D' => 9],
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'B' => ['A' => 3, 'C' => 3, 'D' => 4, 'E' => 7],
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'C' => ['A' => 5, 'B' => 3, 'D' => 2, 'E' => 6, 'F' => 3],
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'D' => ['A' => 9, 'B' => 4, 'C' => 2, 'E' => 2, 'F' => 2],
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'E' => ['B' => 7, 'C' => 6, 'D' => 2, 'F' => 5],
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'F' => ['C' => 3, 'D' => 2, 'E' => 5],
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];
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$source = "A";
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$target = "F";
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$result = Dijkstra($graph, $source, $target);
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extract($result);
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echo "Distance from $source to $target is $distance \n";
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echo "Path to follow : ";
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while (!$path->isEmpty()) {
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echo $path->pop() . "\t";
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}

‎Algorithms/Graph/FloydWarshall.php‎

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<?php
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/*
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* Author: Mizanur rahman <[email protected]>
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*
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*/
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function floydWarshall(array $graph): array {
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$dist = [];
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$dist = $graph;
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$size = count($dist);
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for ($k = 0; $k < $size; $k++)
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for ($i = 0; $i < $size; $i++)
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for ($j = 0; $j < $size; $j++)
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$dist[$i][$j] = min($dist[$i][$j], $dist[$i][$k] + $dist[$k][$j]);
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return $dist;
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}
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$totalVertices = 5;
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$graph = [];
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for ($i = 0; $i < $totalVertices; $i++) {
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for ($j = 0; $j < $totalVertices; $j++) {
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$graph[$i][$j] = $i == $j ? 0 : PHP_INT_MAX;
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}
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}
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$graph[0][1] = $graph[1][0] = 10;
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$graph[2][1] = $graph[1][2] = 5;
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$graph[0][3] = $graph[3][0] = 5;
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$graph[3][1] = $graph[1][3] = 5;
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$graph[4][1] = $graph[1][4] = 10;
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$graph[3][4] = $graph[4][3] = 20;
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$distance = floydWarshall($graph);
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echo "Shortest distance between A to E is:" . $distance[0][4] . "\n";
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echo "Shortest distance between D to C is:" . $distance[3][2] . "\n";

‎Algorithms/Graph/Kruskal.php‎

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<?php
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/*
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* Example code for: PHP 7 Data Structures and Algorithms
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*
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* Author: Mizanur rahman <[email protected]>
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*
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*/
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function Kruskal(array $graph): array {
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$len = count($graph);
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$tree = [];
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$set = [];
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foreach ($graph as $k => $adj) {
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$set[$k] = [$k];
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}
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$edges = [];
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for ($i = 0; $i < $len; $i++) {
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for ($j = 0; $j < $i; $j++) {
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if ($graph[$i][$j]) {
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$edges[$i . ',' . $j] = $graph[$i][$j];
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}
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}
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}
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asort($edges);
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foreach ($edges as $k => $w) {
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list($i, $j) = explode(',', $k);
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$iSet = findSet($set, $i);
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$jSet = findSet($set, $j);
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if ($iSet != $jSet) {
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$tree[] = ["from" => $i, "to" => $j, "cost" => $graph[$i][$j]];
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unionSet($set, $iSet, $jSet);
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}
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}
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return $tree;
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}
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function findSet(array &$set, int $index) {
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foreach ($set as $k => $v) {
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if (in_array($index, $v)) {
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return $k;
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}
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}
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return false;
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}
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function unionSet(array &$set, int $i, int $j) {
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$a = $set[$i];
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$b = $set[$j];
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unset($set[$i], $set[$j]);
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$set[] = array_merge($a, $b);
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}
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$graph = [
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[0, 3, 1, 6, 0, 0],
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[3, 0, 5, 0, 3, 0],
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[1, 5, 0, 5, 6, 4],
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[6, 0, 5, 0, 0, 2],
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[0, 3, 6, 0, 0, 6],
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[0, 0, 4, 2, 6, 0]
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];
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$mst = Kruskal($graph);
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$minimumCost = 0;
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foreach($mst as $v) {
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echo "From {$v['from']} to {$v['to']} cost is {$v['cost']} \n";
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$minimumCost += $v['cost'];
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}
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echo "Minimum cost: $minimumCost \n";
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