class Node(object):
 def __init__(self, item=None, left=None, right=None):
  self.item = item
  self.left = left
  self.right = right
 
 
d = Node("D")
e = Node("E")
b = Node("B", d, e)
f = Node("F")
g = Node("G")
c = Node("C", f, g)
a = Node("A", b, c)
 
 
result = []
 
 
def deep_search(root):
 # 深度遍历 核心：递归
 result.append(root.item)
 if root.left:
  deep_search(root.left)
 if root.right:
  deep_search(root.right)
 return "-->".join(result)
 
 
print deep_search(a)

def wide_search(root, result=[]):
 
 if not result:
  result.append(root.item)
 if root.left:
  result.append(root.left.item)
 if root.right:
  result.append(root.right.item)
 if root.left:
  wide_search(root.left)
 if root.right:
  wide_search(root.right)
 return "-->".join(result)
 
 
print wide_search(a)