fixing dijkstra's algorithm

Author: mirahman

Algorithms/Graph/Dijkstra.php

@@ -1,71 +1,73 @@
-<?php
-
-/* 
- * Author: Mizanur rahman <[email protected]>
- * 
- */
-
-function dijkstra(array $graph, string $source, string $target): array {
-    $dist = [];
-    $pred = [];
-    $Queue = new SplPriorityQueue();
-
-    foreach ($graph as $v => $adj) {
-	$dist[$v] = PHP_INT_MAX;
-	$pred[$v] = null;
-	$Queue->insert($v, min($adj));
-    }
-
-    $dist[$source] = 0;
-
-    while (!$Queue->isEmpty()) {
-	$u = $Queue->extract();
-	if (!empty($graph[$u])) {
-	    foreach ($graph[$u] as $v => $cost) {
-		if ($dist[$u] + $cost < $dist[$v]) {
-		    $dist[$v] = $dist[$u] + $cost;
-		    $pred[$v] = $u;
-		}
-	    }
-	}
-    }
-
-    $S = new SplStack();
-    $u = $target;
-    $distance = 0;
-
-    while (isset($pred[$u]) && $pred[$u]) {
-	$S->push($u);
-	$distance += $graph[$u][$pred[$u]];
-	$u = $pred[$u];
-    }
-
-    if ($S->isEmpty()) {
-	return ["distance" => 0, "path" => $S];
-    } else {
-	$S->push($source);
-	return ["distance" => $distance, "path" => $S];
-    }
-}
-
-$graph = [
-    'A' => ['B' => 3, 'C' => 5, 'D' => 9],
-    'B' => ['A' => 3, 'C' => 3, 'D' => 4, 'E' => 7],
-    'C' => ['A' => 5, 'B' => 3, 'D' => 2, 'E' => 6, 'F' => 3],
-    'D' => ['A' => 9, 'B' => 4, 'C' => 2, 'E' => 2, 'F' => 2],
-    'E' => ['B' => 7, 'C' => 6, 'D' => 2, 'F' => 5],
-    'F' => ['C' => 3, 'D' => 2, 'E' => 5],
-];
-
-$source = "A";
-$target = "F";
-
-$result = dijkstra($graph, $source, $target);
-extract($result);
-
-echo "Distance from $source to $target is $distance \n";
-echo "Path to follow : ";
-
-while (!$path->isEmpty()) {
-    echo $path->pop() . "\t";
+<?php
+
+/*
+ * Author: Mizanur rahman <[email protected]>
+ * 
+ */
+
+function dijkstra(array $graph, string $source, string $target): array {
+    $dist = [];
+    $pred = [];
+    $Queue = new SplPriorityQueue();
+
+    foreach ($graph as $v => $adj) {
+        $dist[$v] = PHP_INT_MAX;
+        $pred[$v] = null;
+        foreach ($adj as $w => $cost) {
+            $Queue->insert($w, $cost);
+        }
+    }
+
+    $dist[$source] = 0;
+
+    while (!$Queue->isEmpty()) {
+        $u = $Queue->extract();
+        if (!empty($graph[$u])) {
+            foreach ($graph[$u] as $v => $cost) {
+                if ($dist[$u] + $cost < $dist[$v]) {
+                    $dist[$v] = $dist[$u] + $cost;
+                    $pred[$v] = $u;
+                }
+            }
+        }
+    }
+
+    $S = new SplStack();
+    $u = $target;
+    $distance = 0;
+
+    while (isset($pred[$u]) && $pred[$u]) {
+        $S->push($u);
+        $distance += $graph[$u][$pred[$u]];
+        $u = $pred[$u];
+    }
+
+    if ($S->isEmpty()) {
+        return ["distance" => 0, "path" => $S];
+    } else {
+        $S->push($source);
+        return ["distance" => $distance, "path" => $S];
+    }
+}
+
+$graph = [
+    'A' => ['B' => 3, 'C' => 5, 'D' => 9],
+    'B' => ['A' => 3, 'C' => 3, 'D' => 4, 'E' => 7],
+    'C' => ['A' => 5, 'B' => 3, 'D' => 2, 'E' => 6, 'F' => 3],
+    'D' => ['A' => 9, 'B' => 4, 'C' => 2, 'E' => 2, 'F' => 2],
+    'E' => ['B' => 7, 'C' => 6, 'D' => 2, 'F' => 5],
+    'F' => ['C' => 3, 'D' => 2, 'E' => 5],
+];
+
+$source = "E";
+$target = "F";
+
+$result = dijkstra($graph, $source, $target);
+extract($result);
+
+echo "Distance from $source to $target is $distance \n";
+echo "Path to follow : ";
+
+while (!$path->isEmpty()) {
+    echo $path->pop() . "\t";
 }