链表中的倒数第k个结点

#include <iostream>
#include <algorithm>
#include "string.h"
#include "stdio.h"
#include <vector>
#include <deque>
#include<stack>
using namespace std;

struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};
class List{
public:

    ListNode* CreatList(int* arr,int len)
    {
        int val;
        ListNode* pHead = new ListNode(arr[0]);
        ListNode* pCurrent=NULL;
        ListNode* rear = pHead;
        int count = 1;
        while(count<len)
        {
            ListNode* pCurrent = new ListNode(arr[count]);
            rear->next = pCurrent;
            rear = pCurrent;
            count++;
        }
        rear->next = NULL;
        return pHead;
    }
    void ShowList(ListNode* pHead)
    {
       while(pHead)
       {
           cout<<pHead->val<<" ";
           pHead = pHead->next;
       }
       cout<<endl;
    }
    ListNode* GetLastNode(ListNode* pHead)
    {
        ListNode* pNode = pHead;
        while(pNode->next!=NULL)
        {
            pNode=pNode->next;
        }
        return pNode;
    }
};
class Sort{
public:
    ListNode* FindKthToTail(ListNode* pListHead, unsigned int k) {

        if(pListHead == NULL||k==0)
            return NULL;
        ListNode* pNode = pListHead;
        ListNode* p = pListHead;
        int count = 0;

        pNode=pListHead;
        for(int i=0;i<k-1;i++)
        {
            if(pNode->next!=NULL)
                pNode = pNode->next;
            else
                return NULL;
        }
        while(pNode->next!=NULL)
        {
            p = p->next;
            pNode=pNode->next;
        }
        return p;
    }
};
int main()
{
    int array[]={3,4,5,1,2,8,7};
    List list;
    Sort sort;
    ListNode* pHead = list.CreatList(array,sizeof(array)/sizeof(array[0]));

    list.ShowList(pHead);
    ListNode* pNode = sort.FindKthToTail(pHead,7);
    cout<<pNode->val<<endl;
    return 0;
}