LC92.java

// Leetcode 92 反转链表II
class Solution {
    public ListNode reverseBetween(ListNode head, int left, int right) {
        ListNode dummy = new ListNode(-1);
        dummy.next = head;
        ListNode pre = dummy;
        ListNode cur = dummy.next;

        for (int i = 0; i < left-1; i++) {
            pre = pre.next;
            cur = cur.next;
        }

        for (int j = 0; j < right-left; j++) {
            ListNode newHead = cur.next;
            cur.next = cur.next.next;
            newHead.next = pre.next;
            pre.next = newHead;
        }


        return dummy.next;
    }
}