【LeetCode】#19删除链表的倒数第N个节点(Remove Nth Node From End of List)
题目描述
给定一个链表，删除链表的倒数第 n 个节点，并且返回链表的头结点。
示例
给定一个链表: 1->2->3->4->5, 和 n = 2.
当删除了倒数第二个节点后，链表变为 1->2->3->5.
Description
Given a linked list, remove the n-th node from the end of list and return its head.
Example
Given linked list: 1->2->3->4->5, and n = 2.
After removing the second node from the end, the linked list becomes 1->2->3->5.
解法
class Solution{
public ListNode removeNthFromEnd(ListNode head, int n){
if(head.next==null){
head = null;
return head;
}
int sum = 0;
ListNode l = head;
while(l!=null){
sum++;
l = l.next;
}
n = sum - n;
l = head;
if(n==0){
return head.next;
}
for(int i=0; i<n-1; i++){
l = l.next;
}
l.next = l.next.next;
return head;
}
}