java - making a Binary Search Tree from a Sorted Doubly Linked List -

hey guys studying programming interview questions , got stuck in one.

i trying recursively don't know start.

this algorithm have far:

 maketree(head, tail){    nodemid = list/2    root = nodemid    root.left = maketree(head, nodemid)    root.right = maketree(nodemid, tail) 

do have right idea? input highly appreciated. thanks!

the major problem see , forgive me if wrong not changing location of list each node. each time recursively call

maketree(head, tail){     nodemid = list/2; 

as far can see inside loop not change part of list goes recursive call. ie have array of ints myints has (0,1,2,3,4,5,6,7,8,9) every time recursion called infinitely fill binary tree number @ list/2 need change value of nodemid each call, use head/tail variables sending.

you not want keep resetting root node either. should using "this" operator set value of current node looking at.

start being start of portion of array looking @ , end being end of portion. recursive calls so. need add in boundaries of recursion

using bst nodes when create new node in tree left , right nodes set null start with. need create new node , call recursion.

node maketree(int head, int tail){     nodemid = (head+tail)/2;     = new node();     if(head < nodemid-1)     {         this.left = maketree(head, nodemid-1);     }     if(nodemid < tail)     {                 this.right = maketree(nodemid, tail);      }     this.setvalue(list[nodemid]);     return this; } 

after recursion done need set value of current node , return node creation. recursively turn sorted array binary search tree. put in proper list coding doubly linked list.

to start recursion

root = maketree(0, list.length());