2.3 delete middle node

Author: amejiarosario

linked-list/delete-middle-node.js

@@ -0,0 +1,66 @@
+
+
+const LinkedList = require('./linkedlist');
+
+LinkedList.prototype.deleteMiddleNode = deleteNode;
+
+let list, node;
+
+// ------ node 2
+
+list = new LinkedList();
+list.add(4);
+list.add(3);
+node = list.add(2);
+list.add(1);
+
+list.deleteMiddleNode(node);
+console.log(list.toString()); // 1 -> 3 -> 4
+
+// ------ node 3
+
+list = new LinkedList();
+list.add(4);
+node = list.add(3);
+list.add(2);
+list.add(1);
+
+list.deleteMiddleNode(node);
+console.log(list.toString()); // 1 -> 2 -> 4
+
+// ------ node 1
+
+list = new LinkedList();
+list.add(4);
+list.add(3);
+list.add(2);
+node = list.add(1);
+
+list.deleteMiddleNode(node);
+console.log(list.toString()); // 2 -> 3 -> 4
+
+// ------ node 4
+
+list = new LinkedList();
+node = list.add(4);
+list.add(3);
+list.add(2);
+list.add(1);
+
+list.deleteMiddleNode(node);
+console.log(list.toString()); // 1 -> 2 -> 3 -> 4
+
+
+// -----------------------
+list.deleteMiddleNode();
+
+/**
+ * O (n)
+ * @param node
+ */
+function deleteNode(node) {
+  if(!node || !node.next) { return; }
+  const next = node.next;
+  node.data = next.data;
+  node.next = next.next
+}

linked-list/linkedlist.js

@@ -11,13 +11,12 @@ class LinkedList {
 
   // O(1)
   add(data) {
+    const newHead = new Node(data);
     if(this.head) {
-      let newHead = new Node(data);
       newHead.next = this.head;
-      this.head = newHead;
-    } else {
-      this.head = new Node(data);
     }
+    this.head = newHead;
+    return newHead;
   }
 
   // O(n)