// Program to test solutions to problem #9 on the cse143 final, fall 2010.
// Fill in your solution to reorder3, then compile and run the program

import java.util.*;

class LinkedIntList {
    public void reorder3() {
        // fill in your solution here
    }

    private ListNode front;  // first value in the list

    // this is the sample solution
    public void reorder3_() {
        if (front != null && front.next != null) {
            ListNode temp = front;
            front = temp.next;
            temp.next = front.next;
            front.next = temp;
            ListNode current = temp.next;
            while (current != null && current.next != null && 
                   current.next.next != null) {
                temp = current.next;
                current.next = temp.next;
                temp.next = current.next.next;
                current.next.next = temp;
                current = temp.next;
            }
        }
    }

    // post: constructs an empty list
    public LinkedIntList() {
        front = null;
    }

    // post: creates a comma-separated, bracketed version of the list
    public String toString() {
        if (front == null)
            return "[]";
        else {
            String result = "[" + front.data;
            ListNode current = front.next;
            while (current != null) {
                result += ", " + current.data;
                current = current.next;
            }
            result += "]";
            return result;
        }
    }

    // post: appends the given value to the end of the list
    public void add(int value) {
        if (front == null)
            front = new ListNode(value);
        else {
            ListNode current = front;
            while (current.next != null)
                current = current.next;
            current.next = new ListNode(value);
        }
    }
}

public class FinalTest9 {
    public static void main(String[] args) {
        for (int i = 0; i <= 15; i++)
            test(i);
    }

    public static void test(int n) {
        LinkedIntList list1 = new LinkedIntList();
        LinkedIntList list2 = new LinkedIntList();
        for (int i = 1; i <= n; i++) {
            list1.add(i);
            list2.add(i);
        }
        boolean fail = false;
        System.out.println("list     = " + list1);
        list1.reorder3_();
        System.out.println("expected = " + list1);
        try {
            list2.reorder3();
        } catch (RuntimeException e) {
            System.out.println("    threw " + e + " with list = " + list2);
            fail = true;
        }
        if (!fail && !list1.toString().equals(list2.toString())) {
            System.out.println("actual   = " + list2);
            fail = true;
        }
        if (fail)
            System.out.println("failed");
        else
            System.out.println("passed");
        System.out.println();
    }
}

class ListNode {
    public int data;       // data stored in this node
    public ListNode next;  // link to next node in the list

    // post: constructs a node with data 0 and null link
    public ListNode() {
        this(0, null);
    }

    // post: constructs a node with given data and null link
    public ListNode(int data) {
        this(data, null);
    }

    // post: constructs a node with given data and given link
    public ListNode(int data, ListNode next) {
        this.data = data;
        this.next = next;
    }
}