实现一种算法,找出单向链表中倒数第 k 个节点。返回该节点的值。
注意:本题相对原题稍作改动
示例:
输入: 1->2->3->4->5 和 k = 2
输出: 4
说明:
给定的 k 保证是有效的。
//leetcode submit region begin(Prohibit modification and deletion)
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public int kthToLast(ListNode head, int k) {
ListNode fast = head;
ListNode slow = head;
for (int i = 0; i < k; i++) {
if (fast == null) {
return -1;
}
fast = fast.next;
}
while (fast != null) {
slow = slow.next;
fast = fast.next;
}
return slow.val;
}
}
//leetcode submit region end(Prohibit modification and deletion)