剑指offer---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) {
        ListNode* p1 = pListHead;
        ListNode* p2 = pListHead;
        int temp = k;

        if(pListHead == NULL || k <= 0)
        {
            return NULL;
        }

        temp--;
        while(temp--)
        {
            /* 链表的长度小于k */
            p2 = p2->next;
            if(p2 == NULL)
            {
                return NULL;
            }
            
        }

        while(p2->next != NULL)
        {
            p1 = p1->next;
            p2 = p2->next;
        }

        return p1;
    }
};