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61. Rotate List

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

For example:
Given 1->2->3->4->5->NULL and k = 2,
return 4->5->1->2->3->NULL.

思路:从length-k(k%length)处切段,把前半段接到后半段。1.扫一遍,扫到末尾的时候把末尾与头连上。2.扫到length-k(k%length)处,也就是3,3.next变成head,3.next变成null

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { val = x; } * } */public class Solution {    public ListNode rotateRight(ListNode head, int k) {    if(head==null||k==0)    {        return head;    }    ListNode node=head;    int size=1;    while(node.next!=null)    {        node=node.next;        size++;    }    node.next=head;    k%=size;    for(int i=0;i<size-k;i++)    {        node=node.next;    }    head=node.next;    node.next=null;    return head;}}

 

61. Rotate List