19. Remove Nth Node From End of List(C++)

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.

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) {
        ListNode myhead(0);
        myhead.next=head;
        ListNode *p=&myhead,*q=&myhead;
        for(int i=0;i<n;i++) p=p->next;
        while(p->next!=NULL){
            p=p->next;
            q=q->next;
        }
        q->next=q->next->next;
        return myhead.next;
    }
};