my solution

Author: amejiarosario

linked-list/kth-to-last.js

@@ -0,0 +1,29 @@
+const LinkedList = require('./linkedlist');
+
+LinkedList.prototype.findKthToLast = function(k) {
+  let length = 0;
+  for(let n = this.head; n; n = n.next) { length++; }
+
+  if(k < 1 || k > length) {
+    return null;
+  }
+
+  let node = this.head;
+  for(let i = 0; i < length - k; i++) { node = node.next; }
+  return node.data;
+};
+
+let list = new LinkedList();
+list.add(4);
+list.add(3);
+list.add(2);
+list.add(1);
+
+console.log(list.toString()); //
+
+console.log(list.findKthToLast(0)); // null
+console.log(list.findKthToLast(1)); // 4
+console.log(list.findKthToLast(2)); // 3
+console.log(list.findKthToLast(3)); // 2
+console.log(list.findKthToLast(4)); // 1
+console.log(list.findKthToLast(5)); // null

linked-list/remove-dups.js

@@ -1,22 +1,21 @@
-let LinkedList = require('./linkedlist');
+const LinkedList = require('./linkedlist');
 
+// O(n)
 LinkedList.prototype.dedub = function () {
   let map = new Map();
-  let n = this.head;
-  map.set(n.data, 1);
+  map.set(this.head.data, 1);
 
-  while(n && n.next) {
+  for(let n = this.head; n && n.next; n = n.next) {
     let data = n.next.data;
     map.set(data, 1);
 
     if(map.get(data)){
       n.next = n.next.next;
     }
-
-    n = n.next;
   }
 };
 
+// O(n^2)
 LinkedList.prototype.dedub2 = function () {
   for(let c = this.head; c; c = c.next) {
     for(let n = c; n && n.next; n = n.next) {