final README

Add recursive implementation for reversing a singly linked list.

Author: pragatiahuja

Linked List/README.markdown

@@ -471,6 +471,7 @@ This will print the list like so:
 
 How about reversing a list, so that the head becomes the tail and vice versa? There is a very fast algorithm for that:
 
+Iterative Approach:
 ```swift
   public func reverse() {
     var node = head
@@ -482,6 +483,18 @@ How about reversing a list, so that the head becomes the tail and vice versa? Th
     }
   }
 ```
+Recursive Approach:
+```swift
+  public func reverse(node: head) {
+    if (!head || !(head.next)) {
+      return head
+    }
+    let temp = reverse(head.next)
+    head.next.next = head;
+    head.next = NULL;
+    return temp;
+  }
+```
 
 This loops through the entire list and simply swaps the `next` and `previous` pointers of each node. It also moves the `head` pointer to the very last element. (If you had a tail pointer you'd also need to update it.) You end up with something like this: