LeetCode (Remove Nth Node From End of List)

Problem:

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.

Solution:

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     ListNode *next;
*     ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* removeNthFromEnd(ListNode* head, int n) {
int length = 0;
ListNode  l(0), *p = &l;
l.next = head;
while(head != NULL){
length++;
head = head->next;
}
for (int i = 1; i <= length; i++){
if (i !=(length - n + 1))
p = p->next;
else
p->next = p->next->next;
}
return l.next;
}
};