每日算法题: Deepest Node in a Binary Tree

Hi, here's your problem today. This problem was recently asked by Google:

You are given the root of a binary tree. Return the deepest node (the furthest node from the root).

Example:

    a

   / \

  b   c

 /

d

The deepest node in this tree is d at depth 3.

Here's a starting point:

class Node(object):

  def __init__(self, val):

    self.val = val

    self.left = None

    self.right = None



  def __repr__(self):

    # string representation

    return self.val





def deepest(node):

  # Fill this in.



root = Node('a')

root.left = Node('b')

root.left.left = Node('d')

root.right = Node('c')



print deepest(root)

# (d, 3)