http://www.programcreek.com/2013/01/leetcode-convert-sorted-list-to-binary-search-tree-java/

ListToBST.java

public static LNode _head;

public BSTNode convert( LNode head ){
  _head = head;
  int len = count( head );
  if( len == 0 ){
    return null;
  }
  return convert( 0, len - 1 );
}

public int count( LNode node ){
  int count = 0;
  while( node != null ){
    node = node.next;
    count++;
  }
  return count;
}

public BSTNode convert( int start, int stop ){
  if( start >= stop ){
    return null;
  }
  int mid = ( start + stop ) / 2;
  BSTNode left = convert( start, mid - 1 );
  BSTNode root = new BSTNode( _head.data );
  _head = _head.next;
  BSTNode right = convert( mid + 1, stop );
  root.left = left;
  root.right = right;
  return root;
}