比价常规的思路

C++ 代码

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* findKthToTail(ListNode* pListHead, int k) {
        if(k<=0||!pListHead){
            return pListHead;
        }
        ListNode* fast=pListHead;

        int num=k;
        while(fast&&(num-->0)){

            fast=fast->next;
        }

        if(num>0){
            return NULL;
        }
        ListNode* slow=pListHead;

        while(fast){

            slow=slow->next;
            fast=fast->next;
        }
        return slow;
    }
};