二叉树转化成Newick格式

Newick Format是表示树的一种方式，具体参见wikipedia https://en.wikipedia.org/wiki/Newick_format。一下代码表示了将二叉树转化成仅保留叶子节点的Newick格式。

比如下图中的树转化成Newick格式为：(A,B,(C,D))



实现的Python代码如下：

class Node:
value = ""
leftChild = None
rightChild = None
def __init__(self, parent):
self.parent = parent
def isLeaf(self):
if (self.leftChild == None and self.rightChild == None):
return True
else:
return False

def convertTreeAux(node, newick):
if node.isLeaf():
newick.append(node.value)
if node.leftChild != None:
newick.append("(")
convertTreeAux(node.leftChild, newick)
newick.append(",")
if node.rightChild != None:
convertTreeAux(node.rightChild, newick)
newick.append(")")

tree =  Node(None)
tree.value = "A"
tree.leftChild = Node(tree)
tree.leftChild.value = "B"
tree.rightChild = Node(tree)
tree.rightChild.value = "C"
tree.rightChild.leftChild = Node(tree.rightChild)
tree.rightChild.leftChild.value = "E"
tree.rightChild.rightChild = Node(tree.rightChild)
tree.rightChild.rightChild.value = "F"

newick = []
convertTreeAux(tree, newick)

print (''.join(newick))