剑指offer--15.链表中倒数第k个节点

/*
struct ListNode {
int val;
struct ListNode *next;
ListNode(int x) :
val(x), next(NULL) {
}
};*/
class Solution {
public:
ListNode* FindKthToTail(ListNode* pListHead, unsigned int k) {
//输入pHeadList为NULL？
//输入K==0?
if (pListHead == NULL||k==0)
return NULL;
ListNode* p1 = pListHead;
ListNode* p2 = pListHead;

while (--k != 0)
{
//输入的K大于整个链表的长度
if(p1->next==NULL)
return NULL;
p1=p1->next;
}
while (p1->next != NULL)
{
p1 = p1->next;
p2 = p2->next;
}
return p2;
}
};