import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.function.*;

class Node
{
    public int val;
    public Node next;
}

class ListUtils
{
    public static void print(Node n) {
        System.out.printf("%d", n.val);
        for(Node cur = n.next; cur != null; cur = cur.next) {
            System.out.printf(", %d", cur.val);
        }
        System.out.println();
    }

    public static Node reverse(Node n) {
        if (n == null) return n;
        Node cur = n.next;
        Node prev = n;
        prev.next = null;
        while(cur != null) {
            Node temp = cur.next;
            cur.next = prev;
            prev = cur;
            cur = temp;
        }
        return prev;
    }

    /* interface Function<T, R> {
     *   T apply(R arg);
     * }
     */
    public static Node map(Node n, Function<Integer, Integer> mapper) {
        for(Node cur = n; cur != null; cur = cur.next) {
            cur.val = mapper.apply(cur.val);
        }
        return n;
    }

    /* interface Predicate<T> {
     *   boolean test(T arg);
     * }
     */
    public static Node filter(Node n, Predicate<Integer> tester) {
        Node root = new Node();
        Node prev = root;
        for(Node cur = n; cur != null; cur = cur.next) {
            if(tester.test(cur.val)) {
                prev.next = cur;
                prev = cur;
            }
        }
        prev.next = null;
        return root.next;
    }

    public static Node filter2(Node n, Predicate<Integer> tester) {
        Node begin = null;
        for(Node cur = n; cur != null; cur = cur.next) {
            if(tester.test(cur.val)) {
                begin = cur;
                break;
            }
        }
        Node prev = begin;
        for(Node cur = begin.next; cur != null; cur = cur.next) {
            if(tester.test(cur.val)) {
                prev.next = cur;
                prev = cur;
            }
        }
        prev.next = null;
        return begin;
    }

    public static void main(String[] args)
    {
        Node n4 = new Node();
        n4.val = 9;
        n4.next = null;
        Node n3 = new Node();
        n3.val = 7;
        n3.next = n4;
        Node n2 = new Node();
        n2.val = 5;
        n2.next = n3;
        Node n1 = new Node();
        n1.val = 3;
        n1.next = n2;
        Node n0 = new Node();
        n0.val = 1;
        n0.next = n1;

        ListUtils.print(n0);
        Node rev = ListUtils.reverse(n0);
        ListUtils.print(rev);
        ListUtils.print(n0);
        Node mapped = ListUtils.map(
            rev,
            i -> i * 3 - 1
        );
        ListUtils.print(mapped);
        Node filtered = ListUtils.filter2(
            mapped,
            i -> i % 4 == 0
        );
        ListUtils.print(filtered);
    }
}