Rotate List (Medium)

Description

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.

Analysis

简单题

My Solution

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//C++
/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
    int getlength(ListNode *head){
        int len = 0;
        while(head){
            len++;
            head = head->next;
        }
        return len;
    }
public:
    ListNode *rotateRight(ListNode *head, int k) {
        if(head==NULL)  return NULL;
        ListNode *p = head,*q,*ans;
        int len = getlength(p) , num = 0;
        k = k%len;
        if(k==0)    return head;
        p = head;
        while(p){
            num++;
            if(num+k==len)
                break;
            p = p->next;
        }
        ans = q = p->next;
        p->next = NULL;
        while(q->next)
            q = q->next;
        q->next = head;
        
        return ans;
    }
};