反转部分单向链表

package chapter_2_listproblem;

public class Problem_05_ReversePartList {

    public static class Node {
        public int value;
        public Node next;

        public Node(int data) {
            this.value = data;
        }
    }

    public static Node reversePart(Node head, int from, int to) {
        int len = 0;
        Node node1 = head;
        Node fPre = null;
        Node tPos = null;
        while (node1 != null) {
            len++;
            fPre = len == from - 1 ? node1 : fPre;
            tPos = len == to + 1 ? node1 : tPos;
            node1 = node1.next;
        }
        if (from > to || from < 1 || to > len) {
            return head;
        }
        node1 = fPre == null ? head : fPre.next;
        Node node2 = node1.next;
        node1.next = tPos;
        Node next = null;
        while (node2 != tPos) {
            next = node2.next;
            node2.next = node1;
            node1 = node2;
            node2 = next;
        }
        if (fPre != null) {
            fPre.next = node1;
            return head;
        }
        return node1;
    }

    public static void printLinkedList(Node head) {
        System.out.print("Linked List: ");
        while (head != null) {
            System.out.print(head.value + " ");
            head = head.next;
        }
        System.out.println();
    }

    public static void main(String[] args) {
        Node head = null;
        printLinkedList(head);
        head = reversePart(head, 1, 1);
        printLinkedList(head);

        head = new Node(1);
        printLinkedList(head);
        head = reversePart(head, 1, 1);
        printLinkedList(head);

        head = new Node(1);
        head.next = new Node(2);
        printLinkedList(head);
        head = reversePart(head, 1, 2);
        printLinkedList(head);

        head = new Node(1);
        head.next = new Node(2);
        head.next.next = new Node(3);
        printLinkedList(head);
        head = reversePart(head, 2, 3);
        printLinkedList(head);

        head = new Node(1);
        head.next = new Node(2);
        head.next.next = new Node(3);
        printLinkedList(head);
        head = reversePart(head, 1, 3);
        printLinkedList(head);

    }

}