CC150 4.4

4.4 Given a binary search tree, design an algorithm which creates a linked list of all the nodes at each depth (i.e., if you have a tree with depth D, you’ll have D linked lists).

List<List<Node>> build(Node root)
{
  List<List<Node>> toReturn = initList();
  build(root, 0, toReturn);
  return toReturn;
}

private void build(Node node, int dep, List<List<Node>> lists)
{
  if (node == null)
    return;
  
  List<Node> list = lists.get(dep);
  if (list == null) list = initList();
  list.add(node);
  
  build(node.left, dep + 1, lists);
  build(node.right, dep + 1, lists);
}

CC150 4.4

原文：http://7371901.blog.51cto.com/7361901/1583043