22. 链表中倒数第k个节点

参考链接

牛客网-剑指Offer

帅地

LeetCode

个人尝试

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode trainingPlan(ListNode head, int cnt) {
        if (head == null) return null;
        //求链表长度
        int len = 0;
        ListNode cur = head;
        while (cur != null) {
            cur = cur.next;
            len++;
        }
        //倒数第一个 == 下标为 len - 1
        cur = head;
        int num = 0;
        int delta = len - cnt;
        while(num < delta) {
            cur = cur.next;
            num++;
        }
        return cur;
    }
}

优秀题解

class Solution {
    public ListNode trainingPlan(ListNode head, int cnt) {
        ListNode former = head, latter = head;
        for(int i = 0; i < cnt; i++) {
            if(former == null) return null;
            former = former.next;
        }
        while(former != null) {
            former = former.next;
            latter = latter.next;
        }
        return latter;
    }
}

作者：Krahets
链接：https://leetcode.cn/problems/lian-biao-zhong-dao-shu-di-kge-jie-dian-lcof/solutions/117507/mian-shi-ti-22-lian-biao-zhong-dao-shu-di-kge-j-11/
来源：力扣（LeetCode）
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