LeetCode "Remove Nth Node From End of List"

class Solution {
public:
ListNode *removeNthFromEnd(ListNode *head, int n) {

ListNode *p = NULL;
ListNode *p0 = head;
ListNode *p1 = head;
ListNode *pre1 = NULL;
while (--n)        p0 = p0->next;

while (p0->next)
{
p0 = p0->next;
pre1 = p1;
p1 = p1->next;
}
if (p1 == head) p = head->next;
else
{
pre1->next = p1->next;
p = head;
}
return p;
}
};