Remove Nth Node from End of List

1. Problem

Removes the last nth node of the linked list and returns the list header. One traversal completes

return Its head. For example,   1->2->3->4->5, and n = 2.    1->2->3->5 do the in one pass.

2. Solution

With two pointers:

• P: The previous node pointing to the possible point of omission;
• Q:q-p = n;

For ease of handling, add an empty node in front of the linked list. The code is as follows:

1 /**2 * Definition for singly-linked list.3 * public class ListNode {4 * int val;5 * ListNode Next;6 * ListNode (int x) {val = x;}7  * }8  */9  Public classSolution {Ten      PublicListNode Removenthfromend (ListNode head,intN) { One         if(Head = =NULL ) A             returnhead; -         //Create a new head node so the we can always remove P.next -ListNode Newhead =NewListNode (0); theNewhead.next =head; -ListNode p = newhead;//Point to the previous node before to-be-deleted node -ListNode q = head;//q-p = n; -         intCount = 1;//To find the first satisfied Q; +          for(; q.next!=NULL&& count<n; count++, q =q.next); -         //The to-be-deleted node exists +         if(Count = =N) { A              while(Q.next! =NULL ){ atp =P.next; -Q =Q.next; -             } -P.next =P.next.next; -         } -         returnNewhead.next; in     } -}

Remove Nth Node from End of List