LinkedList: implement emptyList and listOf

src/main/kotlin/data_structures/linked_list/LinkedList.kt

@@ -198,6 +198,8 @@ class LinkedList<T> : Iterable<Node<T>> {
     override fun iterator(): Iterator<Node<T>> {
         return NodeIterator(this)
     }
+
+    companion object
 }
 
 /**
@@ -210,3 +212,22 @@ inline fun <reified E> LinkedList<E>.toArray(): Array<E?> {
     }
     return newArray
 }
+
+/**
+ * Creates an empty linked list.
+ */
+fun <T> LinkedList.Companion.emptyList(): LinkedList<T> {
+    return LinkedList()
+}
+
+/**
+ * Constructs a linked list from a variable number of arguments.
+ */
+fun <T> LinkedList.Companion.listOf(vararg items: T): LinkedList<T> {
+    val linkedList = LinkedList<T>()
+    items.forEach {
+        linkedList.append(it)
+    }
+    return linkedList
+}
+

src/test/kotlin/data_structures/linked_list/LinkedListTest.kt

@@ -1,6 +1,8 @@
 package data_structures.linked_list
 
 import dev.nuculabs.dsa.data_structures.linked_list.LinkedList
+import dev.nuculabs.dsa.data_structures.linked_list.emptyList
+import dev.nuculabs.dsa.data_structures.linked_list.listOf
 import dev.nuculabs.dsa.data_structures.linked_list.toArray
 import org.junit.jupiter.api.Test
 
@@ -289,4 +291,21 @@ class LinkedListTest {
         // Assert
         assertContentEquals(arrayOf("First", "Second"), result)
     }
+
+    @Test
+    fun emptyList() {
+        // Test
+        val list = LinkedList.emptyList<String>()
+        // Assert
+        assertEquals(0, list.size())
+    }
+
+    @Test
+    fun listOf() {
+        // Test
+        val list = LinkedList.listOf("One", "Two", "Three")
+        // Assert
+        assertEquals(3, list.size())
+        assertContentEquals(listOf("One", "Two", "Three"), list.toJavaList())
+    }
 }