all tasks

Task/Sorting-algorithms-Strand-sort/PHP/sorting-algorithms-strand-sort.php

@@ -0,0 +1,38 @@
+$lst = new SplDoublyLinkedList();
+foreach (array(1,20,64,72,48,75,96,55,42,74) as $v)
+    $lst->push($v);
+foreach (strandSort($lst) as $v)
+    echo "$v ";
+
+function strandSort(SplDoublyLinkedList $lst) {
+    $result = new SplDoublyLinkedList();
+    while (!$lst->isEmpty()) {
+        $sorted = new SplDoublyLinkedList();
+        $remain = new SplDoublyLinkedList();
+        $sorted->push($lst->shift());
+        foreach ($lst as $item) {
+            if ($sorted->top() <= $item) {
+                $sorted->push($item);
+            } else {
+                $remain->push($item);
+            }
+        }
+        $result = _merge($sorted, $result);
+        $lst = $remain;
+    }
+    return $result;
+}
+
+function _merge(SplDoublyLinkedList $left, SplDoublyLinkedList $right) {
+    $res = new SplDoublyLinkedList();
+    while (!$left->isEmpty() && !$right->isEmpty()) {
+        if ($left->bottom() <= $right->bottom()) {
+            $res->push($left->shift());
+        } else {
+            $res->push($right->shift());
+        }
+    }
+    foreach ($left as $v)  $res->push($v);
+    foreach ($right as $v) $res->push($v);
+    return $res;
+}