Bdtjtk

Sorry if this isn't appropriate, but I'm really try to work on my algorithm skills.

static public ListNode RemoveNthNodeFromEndOf(ListNode head, int n)

{

    if (head == null || n == 0) return head;

    ListNode dummy = new ListNode(0);

    dummy.next = head;

    ListNode p = dummy , q = dummy.next;

    int i = 0;

    while (q.next != null)

    {

        if (i >= n - 1) p = p.next;

        q = q.next;

        i++;

    }

    p.next = p.next.next;

    return dummy.next;

}

I completely understand what they did here, I just don't understand how you get to that answer and I would honestly like to figure out that skill. Basically, how do you approach this and think, i >= n-1 then p should start to follow q. Steps to the thought to get there I guess? Not

You want a pointer n from the end. But you can't move backwards, and you can't see forwards. What to do?

Suppose you're in a dark corridor and someone tells you the light switch is three meters from the end. It's too dark to see three meters, so you pick up the proverbial ten-foot pole, hold it pointing forward, and walk down the corridor until the pole touches the end.

Here, we don't have a pole handy, but we can build one by making a second pointer and stepping it n times. Now, we have two pointers n steps apart and we can advance both in parallel until the advance pointer hits the wallend of the list. Then the other pointer is n steps from the end.

How to come up with these solutions? Both come about from the same thought process: "I could do this if only I had something walking ahead of me." I guess practice helps. Really wanting to solve the problem helps, as does believing the problem has a solution. Add a bit of creativity and maybe a bit of seeing the world as you would like it to be. In short, the same way you solve any problem.