QuestionD.java

package Q2_02_Return_Kth_To_Last;

import CtCILibrary.*;

public class QuestionD {
	
	public static LinkedListNode nthToLast(LinkedListNode head, int k) {
		LinkedListNode p1 = head;
		LinkedListNode p2 = head;
		
		/* Move p1 k nodes into the list.*/
		for (int i = 0; i < k; i++) {
			if (p1 == null) return null; // Out of bounds
			p1 = p1.next;
		}
		
		/* Move them at the same pace. When p1 hits the end, 
		 * p2 will be at the right element. */
		while (p1 != null) {
			p1 = p1.next;
			p2 = p2.next;
	  	}
	  	return p2;
	}
	
	public static void main(String[] args) {
		int[] array = {0, 1, 2, 3};
		LinkedListNode head = AssortedMethods.createLinkedListFromArray(array);
		for (int i = 0; i <= array.length + 1; i++) {
			LinkedListNode node = nthToLast(head, i);
			String nodeValue = node == null ? "null" : "" + node.data;
			System.out.println(i + ": " + nodeValue);
		}
	}

}