Data commit

Task/Dijkstras-algorithm/PHP/dijkstras-algorithm.php

@@ -0,0 +1,69 @@
+<?php
+function dijkstra($graph_array, $source, $target) {
+    $vertices = array();
+    $neighbours = array();
+    foreach ($graph_array as $edge) {
+        array_push($vertices, $edge[0], $edge[1]);
+        $neighbours[$edge[0]][] = array("end" => $edge[1], "cost" => $edge[2]);
+        $neighbours[$edge[1]][] = array("end" => $edge[0], "cost" => $edge[2]);
+    }
+    $vertices = array_unique($vertices);
+
+    foreach ($vertices as $vertex) {
+        $dist[$vertex] = INF;
+        $previous[$vertex] = NULL;
+    }
+
+    $dist[$source] = 0;
+    $Q = $vertices;
+    while (count($Q) > 0) {
+
+        // TODO - Find faster way to get minimum
+        $min = INF;
+        foreach ($Q as $vertex){
+            if ($dist[$vertex] < $min) {
+                $min = $dist[$vertex];
+                $u = $vertex;
+            }
+        }
+
+        $Q = array_diff($Q, array($u));
+        if ($dist[$u] == INF or $u == $target) {
+            break;
+        }
+
+        if (isset($neighbours[$u])) {
+            foreach ($neighbours[$u] as $arr) {
+                $alt = $dist[$u] + $arr["cost"];
+                if ($alt < $dist[$arr["end"]]) {
+                    $dist[$arr["end"]] = $alt;
+                    $previous[$arr["end"]] = $u;
+                }
+            }
+        }
+    }
+    $path = array();
+    $u = $target;
+    while (isset($previous[$u])) {
+        array_unshift($path, $u);
+        $u = $previous[$u];
+    }
+    array_unshift($path, $u);
+    return $path;
+}
+
+$graph_array = array(
+                    array("a", "b", 7),
+                    array("a", "c", 9),
+                    array("a", "f", 14),
+                    array("b", "c", 10),
+                    array("b", "d", 15),
+                    array("c", "d", 11),
+                    array("c", "f", 2),
+                    array("d", "e", 6),
+                    array("e", "f", 9)
+               );
+
+$path = dijkstra($graph_array, "a", "e");
+
+echo "path is: ".implode(", ", $path)."\n";