時間: 2019-12-12 7:41 PM
題目地址: https://leetcode.com/problems/rotate-list
Given a linked list, rotate the list to the right by k places, where k is non-negative.
給定一個鏈表，將列表向右旋轉k個位置，其中k爲非負數。
Example 1:
Input: 1->2->3->4->5->NULL, k = 2
Output: 4->5->1->2->3->NULL
Explanation:
rotate 1 steps to the right: 5->1->2->3->4->NULL
rotate 2 steps to the right: 4->5->1->2->3->NULL
Example 2:
Input: 0->1->2->NULL, k = 4
Output: 2->0->1->NULL
Explanation:
rotate 1 steps to the right: 2->0->1->NULL
rotate 2 steps to the right: 1->2->0->NULL
rotate 3 steps to the right: 0->1->2->NULL
rotate 4 steps to the right: 2->0->1->NULL
Solution:
public ListNode rotateRight(ListNode head, int k) {
if (null == head || null == head.next) {
return head;
}
ListNode point = head;
ListNode tail = null;
int len = 0;
while (null != point) {
tail = point;
++len;
point = point.next;
}
int pos = (len - (k % len)) - 1;
if (pos == len - 1) {
return head;
}
point = head;
for (int i = 0; i < pos; ++i) {
point = point.next;
}
tail.next = head;
head = point.next;
point.next = null;
return head;
}
Runtime: 0 ms, faster than 100.00% of Java online submissions for Rotate List.
Memory Usage: 38 MB, less than 75.86% of Java online submissions for Rotate List.
