/*
 *  Copyright (C) 2009  E.Albert, P.Arenas, S.Genaim, G.Puebla, and D.Zanardini
 *                      https://costa.ls.fi.upm.es
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package pubs;
/**
 * This class implements several operations on singly linked lists
 * 
 * @author E.Albert, P.Arenas, S.Genaim, and G.Puebla
 * 
 */
public class MergeList {

	private int head;
	private MergeList tail;

	public MergeList(int head, MergeList tail) {
		this.head = head;
		this.tail = tail;
	}

	public MergeList append(MergeList other) {
		if (tail == null) return new MergeList(head,other);
		else return new MergeList(head,tail.append(other));
	}

	public MergeList reverseAcc(MergeList acc) {
		if (tail == null) return new MergeList(head,acc);
		else return tail.reverseAcc(new MergeList(head,acc));
	}

	public MergeList reverse() {
		if (tail == null) return this;
		else return tail.reverse().append(new MergeList(head,null));
	}

	/**
	 * Returns a sorted list which is the result of merging 
	 * the sorted list "this" with the sorted list other.
	 * 
	 * @param other
	 * @return
	 */
	public MergeList merge(MergeList other) {
		if (other == null) return this;
		else if (head <= other.head)
			if (tail != null) return new MergeList(head,tail.merge(other));
			else return new MergeList(head,other);
		else return new MergeList(other.head,merge(other.tail));
	}

	public static void main(String[] args) {

		// Prepare the test
		MergeList test = new MergeList(1,null);
		for (int i = 3; i <= 21; i = i + 2) {
			MergeList aux = new MergeList(i,null);
			test = test.append(aux);
		}
		MergeList other = new MergeList(2,null);
		for (int i = 4; i <= 22; i = i + 2) {
			MergeList aux = new MergeList(i,null);
			other = other.append(aux);
		}
		// Test
		MergeList result = test.merge(other);

	

	}
}