A complete Binary Search Tree with level order insert in Java

Question

We got an assignment where we need to code:

• A Binary Search Tree
• The Tree has to be complete, not perfect

Answer 1

I think you should do it this manner (code is in C#, but shouldn't be very hard to convert it to Java):

//list should be sorted
public void myFunc(List list){
        Queue> queue = new Queue>();
         queue.Enqueue(list);

        while(queue.Any()){
            List l = queue.Dequeue();
            int rindex = findRoot(l);
            //print r or store it somewhere
            Console.WriteLine(l.ElementAt(rindex));
            List leftlist = l.GetRange(0, rindex);
            List rightlist = l.GetRange(rindex + 1, l.Count-rindex-1);
            //leftlist = list l from index 0 to r-1; rightlist = list l from index r+1 to end.
            if (leftlist.Any())
            {
                queue.Enqueue(leftlist);
            }

            if (rightlist.Any())
            {
                queue.Enqueue(rightlist);
            }

        }

    }

******EDIT: *********************************************

For finding the root every time you have a list of size n, do the following:

public int findRoot(List list)
        {
            int n = list.Count;

            double h = Math.Ceiling(Math.Log(n + 1, 2)) - 1;

            double totNodesInCompleteBinaryTreeOfHeighthMinusOne = Math.Pow(2, h) - 1;
            double nodesOnLastLevel = n - totNodesInCompleteBinaryTreeOfHeighthMinusOne;

            double nodesOnLastLevelInRightSubtree = 0;

            if (nodesOnLastLevel > Math.Pow(2, h - 1))
            {
                nodesOnLastLevelInRightSubtree = nodesOnLastLevel - Math.Pow(2, h - 1);
            }

            int rindex = (int)(n - nodesOnLastLevelInRightSubtree - 1 - ((totNodesInCompleteBinaryTreeOfHeighthMinusOne - 1) / 2));

            return rindex;
        }