package question;

/**
 * @author Roderland
 * @since 1.0
 */
public class Question92 {
 public static void main(String[] args) {
 System.out.println(new Question92().reverseBetween(new ListNode(5), 1, 1).val);
 }

 public ListNode reverseBetween(ListNode head, int left, int right) {
 ListNode slow = head;
 ListNode fast = head;
 for (int i = 0; i < right - left; i++) {
 fast = fast.next;
 }
 ListNode a = null;
 for (int i = 1; i < left; i++) {
 a = slow;
 slow = slow.next;
 fast = fast.next;
 }
 ListNode b = fast.next;
 ListNode pre = a;
 ListNode cur = slow;
 while (cur != b) {
 ListNode next = cur.next;
 cur.next = pre;
 pre = cur;
 cur = next;
 }
 if (slow != null) slow.next = b;
 if (a != null) a.next = pre;
 else head = fast;
 return head;
 }
}