Problem

Given a list, rotate the list to the right by k places, where k is non-negative.

Example
Given 1->2->3->4->5 and k = 2, return 4->5->1->2->3.

思路

• 错误的思路

  1. find the len
  2. split the list from the last second place
  3. append left part to the end of right part

  4. 错误原因:

  5. 当 k > len的时候, 应该继续从右到左数

• 所以加上 k %= len

    public ListNode rotateRight(ListNode head, int k) {
        // 1. find the len
        ListNode curt = head;
        int len = 1;
        while (curt != null && curt.next != null) {
            curt = curt.next;
            len++;
        }
        ListNode lastNode = curt;

        k %= len;
        if (k == 0) return head;

        // 2. split the list from the last second place
        curt = head;
        ListNode prev = null;
        for (int i = 1; i <= len - k; i++) {
            prev = curt;
            curt = curt.next;
        }
        prev.next = null;

        // 3. append left part to the end of right part
        lastNode.next = head;

        return curt;
    }