题解 | #链表中倒数最后k个结点#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 *	ListNode(int x) : val(x), next(nullptr) {}
 * };
 */
class Solution {
public:
    ListNode* FindKthToTail(ListNode* pHead, int k) {
        /*int length = 0;
        ListNode* cur = pHead;
        while( cur )
        {
            ++length;
            cur = cur->next;
        }
        if(length < k) return nullptr;
        length -= k;
        while(length--)
        {
            pHead = pHead->next;
        }
        return pHead;*/

        ListNode* fast = pHead ,*slow = pHead;
        for(int i=0; i < k ; ++i)
        {
            if(fast == nullptr) return fast;
            fast = fast->next;
        }
        while(fast!=nullptr)
        {
            slow = slow->next;
            fast = fast->next;
        }
        return slow;
    }
};