1.题目
19. 删除链表的倒数第 N 个结点
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给你一个链表,删除链表的倒数第 n 个结点,并且返回链表的头结点。
示例 1:
输入:head = [1,2,3,4,5], n = 2 输出:[1,2,3,5]
示例 2:
输入:head = [1], n = 1 输出:[]
示例 3:
输入:head = [1,2], n = 1 输出:[1]
提示:
快慢指针,要注意的是返回的值,快指针先走,然后满指针再走
代码
/**
* Definition for singly-linked list.
* function ListNode(val, next) {
* this.val = (val===undefined ? 0 : val)
* this.next = (next===undefined ? null : next)
* }
*/
/**
* @param {ListNode} head
* @param {number} n
* @return {ListNode}
*/
var removeNthFromEnd = function(head, n) {
let dum = new ListNode(-1);
dum.next = head;
let fast = dum;
let slow = dum;
for(let i = 0; i < n ; i++) {
fast = fast.next;
}
while(fast && fast.next) {
fast = fast.next;
slow = slow.next;
}
slow.next = slow.next.next;
return dum.next;
};