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.

/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* struct ListNode *next;
* };
*/
struct ListNode* removeNthFromEnd(struct ListNode* head, int n) {
struct ListNode* front=head;
struct ListNode* back=head;
for(int i=0;i<n;i++){
back=back->next;
if(!back){
return head->next;
}
}
while(back->next){
back=back->next;
front=front->next;
}
front->next= front->next->next;
return head;
}