【每日一题】【leetcode】26. 链表-链表中倒数第k个节点

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* getKthFromEnd(ListNode* head, int k) {
        ListNode *lp = head, *rp = head;
        while (rp != NULL) {
            rp = rp->next;
            if (k > 0) {
                k--;
            } else {
                lp = lp->next;
            }
        }
        return lp;
        
    }
};

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* getKthFromEnd(ListNode* head, int k) {
        ListNode *lp = head, *rp = head;
        while (rp->next != NULL) {
            rp = rp->next;// 结束时，rp是最后一个节点，而非NULL
            if (k > 1) {
                k--;
            } else {
                lp = lp->next;
            }
        }
        return lp;
        
    }
};