[] 61. Rotate List LeetCode rotation list (Medium) (JAVA)
Topic Address: https://leetcode.com/problems/rotate-list/
Subject description:
Given a linked list, rotate the list to the right by k places, where k is non-negative.
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
Subject to the effect
Given a list, the list of rotation, each of the node list to the right by k positions, wherein k is non-negative.
Problem-solving approach
1, the calculated chain length (because of: k> len), and then calculates the movement position of the real needs: len% K
2, identify the need to move a Node, preNode
. 3, disconnection preNode the next, all the node to link
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode rotateRight(ListNode head, int k) {
if (head == null) return head;
ListNode temp = head;
int count = 1;
while (temp != null) {
if (temp.next == null) break;
temp = temp.next;
count++;
}
ListNode tail = temp;
k = k % count;
temp = head;
for (int i = 1; i < count - k; i++) {
temp = temp.next;
}
tail.next = head;
ListNode res = temp.next;
temp.next = null;
return res;
}
}
When execution: 1 ms, beat the 87.45% of all users to submit in Java
memory consumption: 37.9 MB, defeated 14.53% of all users to submit in Java
