给定顺序的树的建立

python

今天看到群友发了张照片，一道笔试题。。
Date Structure
For Inorder and Preorder traversals

inorder = + d c a - b / * e
preorder = a d + c - * b / e

please construct this tree

大意
中序和前序遍历如题，请构造此树！

刚好最近在啃算法，练练手！用手画了画，树应该是这样的。
。
下面就用代码测试下看看。

# code=utf-7
class Node:
    def __init__(self, key):
        self.val = key
        self.left = None
        self.right = None
def inorderprint(root):
    if root:
        inorderprint(root.left)
        print(root.val)
        inorderprint(root.right)
def preprint(root):
    if root:
        print(root.val)
        preprint(root.left)
        preprint(root.right)
def postprint(root):
    if root:
        postprint(root.left)
        postprint(root.right)
        print(root.val)
root = Node('a')
root.left = Node('d')
root.left.left = Node('+')
root.left.right = Node('c')
root.right = Node('-')
root.right.right = Node('*')
root.right.right.left = Node('b')
root.right.right.right = Node('e')
root.right.right.left.right = Node('/')
>>> inorderprint(root)
+
d
c
a
-
b
/
*
e
>>> preprint(root)
a
d
+
c
-
*
b
/
e
>>> postprint(root)
+
c
d
/
b
e
*
-
a

正确！顺便把后续的也打印了！

参考

Tree Traversals