[LeetCode] 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
.
/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */ class Solution { public: ListNode *rotateRight(ListNode *head, int k) { if(k==0 || head==NULL || head->next == NULL) return head; int len=0; ListNode *p = head; while(p){ len++; p = p->next; } while(len<k){ k -= len; } ListNode *Pfast = head,*Pslow =head,*h = head; int i; for(i=0;Pfast!=NULL && i<k+1;i++){ Pfast = Pfast->next; } while(Pfast!=NULL){ Pfast = Pfast->next; Pslow = Pslow->next; }//end while; if(Pslow == head && i< k+1) return head; h = Pslow->next; Pslow->next = NULL; Pslow = h; while(Pslow && Pslow->next) Pslow = Pslow->next; Pslow->next = head; return h; }//end func };