092.Reverse Linked List II

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Solution 1: accepted 3ms 93%

Well, it shouldn’t be this long. Can we optimize it?

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public ListNode reverseBetween(ListNode head, int m, int n) {
    ListNode dummy = new ListNode(0);
    dummy.next = head;
    head = dummy;
    for (int i = 1; i < m; i++) {
        head = head.next;
    }
    ListNode cur = head.next;
    ListNode rev = null; // reversed part
    ListNode tail = null;
    int count = n - m;
    for (int i = m; i <= n; i++) {
        ListNode temp = cur.next;
        if (rev != null) {
            cur.next = rev;
            rev = cur;
        } else {
            rev = cur;
            tail = cur;
            rev.next = null;
        }
        cur = temp;
        count--;
        if (i >= n) {
            tail.next = cur;
            head.next = rev;
        }
    }
    return dummy.next;
}