19. Remove Nth Node From End of List

Given a linked list, remove the nth node from the end of list and return its head.

For 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.

Note:

Given n will always be valid.

Try to do this in one pass.

Code

/**
* Definition for singly-linked list.
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) { val = x; }
* }
*/
public class Solution {
public ListNode removeNthFromEnd(ListNode head, int n) {
if (head == null || head.next == null)
return null;
ListNode temp = head;
LinkedList<ListNode> linkedList = new LinkedList<>();
while (temp != null) {
linkedList.add(temp);
temp = temp.next;
}
int size = linkedList.size();
if (size == n) {
return head.next;
}
ListNode pre = linkedList.get(size - n -1);
if (n == 1) {
pre.next = null;
} else {
pre.next = linkedList.get(size - n + 1);
}
return head;
}
}