/**

* Remove Nth Node From End of List

* Double pointer.

*

* cpselvis(cpselvis@gmail.com)

* August 18th, 2016

*/

#include<iostream>

using namespace std;

struct ListNode {

int val;

ListNode *next;

ListNode(int x) : val(x), next(NULL) {}

};

class Solution {

public:

ListNode* removeNthFromEnd(ListNode* head, int n) {

ListNode *fast = head, *slow = head;

while (n --)

{

fast = fast -> next;

}

while (fast == NULL)

{

return head -> next;

}

while (fast -> next != NULL)

{

fast = fast -> next;

slow = slow -> next;

}

slow -> next = slow -> next -> next;

return head;

}

};

int main(int argc, char **argv)

{

Solution s;

ListNode *p = new ListNode(1);

// p -> next = new ListNode(2);

// p -> next -> next = new ListNode(3);

ListNode *ret = s.removeNthFromEnd(p, 1);

cout << ret -> val << endl;

}