剑指offer-链表中倒数第k个结点

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) :
            val(x), next(NULL) {
    }
};*/
class Solution {
public:
    ListNode* FindKthToTail(ListNode* pListHead, unsigned int k) {
        if(pListHead==NULL||k==0)
            return NULL;
        ListNode* p = pListHead;
        ListNode* q = pListHead;
        int i=1;
        while(p->next!=NULL)
        {
            p=p->next;
            i++;
        }
        if(k>i) return NULL;
        while(i-k>0)
        {
            q=q->next;
            i--;
        }
        return q;
    
    }
};