Implement nthToLast method for linked list

cracking-the-coding-interview/chapter-two-linked-lists/NthToLast.java

@@ -0,0 +1,23 @@
+public class NthToLast {
+  public static LinkedList nthToLast(LinkedListNode head, int n) {
+    if (head == null || n <= 0) return null;
+
+    LinkedListNode p1 = head;
+    LinkedListNode p2 = head;
+
+    // Move p2 ahead by n nodes
+    for (int i = 0; i < n; i++) {
+      if (p2 == null) return null; // n is larger than the list length
+      p2 = p2.next;
+    }
+
+    // Move both pointers until p2 hits the end
+    while (p2 != null) {
+      p1 = p1.next;
+      p2 = p2.next;
+    }
+
+    // p1 now points to the Nth to last node
+    return p1;
+  }
+}