reverse singlylinkedlist

realDuYuanChao · realDuYuanChao · commit bd40790d8358 · 2020-12-04T11:32:10.000+08:00
diff --git a/src/main/java/com/examplehub/datastructures/linkedlist/SinglyLinkedList.java b/src/main/java/com/examplehub/datastructures/linkedlist/SinglyLinkedList.java
@@ -179,6 +179,25 @@ public E deleteNth(int index) {
     return deleteNode.data;
   }
 
+  /**
+   * Reverse singlyLinkedList
+   *
+   * @return reversed singlyLinkedList.
+   */
+  public SinglyLinkedList<E> reverse() {
+    Node<E> prev = null;
+    Node<E> current = this.head;
+    Node<E> next = null;
+    while (current != null) {
+      next = current.next;
+      current.next = prev;
+      prev = current;
+      current = next;
+    }
+    this.head = prev;
+    return this;
+  }
+
   @Override
   public String toString() {
     StringJoiner joiner = new StringJoiner("->");
diff --git a/src/test/java/com/examplehub/datastructures/linkedlist/SinglyLinkedListTest.java b/src/test/java/com/examplehub/datastructures/linkedlist/SinglyLinkedListTest.java
@@ -174,4 +174,12 @@ void testInsertTail() {
     singlyLinkedList.insertTail("1", "2", "3", "4", "5");
     assertEquals("1->2->3->4->5->NULL", singlyLinkedList.toString());
   }
+
+  @Test
+  void testReverse(){
+    SinglyLinkedList<String> singlyLinkedList = new SinglyLinkedList<>();
+    singlyLinkedList.insertTail("1", "2", "3", "4", "5");
+    assertEquals("1->2->3->4->5->NULL", singlyLinkedList.toString());
+    assertEquals("5->4->3->2->1->NULL", singlyLinkedList.reverse().toString());
+  }
 }

Original file line number	Diff line number	Diff line change
`@@ -174,4 +174,12 @@ void testInsertTail() {`
`174`	`174`	`singlyLinkedList.insertTail("1", "2", "3", "4", "5");`
`175`	`175`	`assertEquals("1->2->3->4->5->NULL", singlyLinkedList.toString());`
`176`	`176`	`}`
	`177`	`+`
	`178`	`+ @Test`
	`179`	`+ void testReverse(){`
	`180`	`+ SinglyLinkedList<String> singlyLinkedList = new SinglyLinkedList<>();`
	`181`	`+ singlyLinkedList.insertTail("1", "2", "3", "4", "5");`
	`182`	`+ assertEquals("1->2->3->4->5->NULL", singlyLinkedList.toString());`
	`183`	`+ assertEquals("5->4->3->2->1->NULL", singlyLinkedList.reverse().toString());`
	`184`	`+ }`
`177`	`185`	`}`