在 Python 中将值插入二叉树

Question

I need to add values to my Binary Tree (Node).

Here is my class:

class Node:
def __init__(self, key):
    self.left = None
    self.right = None
    self.val = key

def __str__(self):
    return "{}".format(self.val)


file = open("/home/dzierzen/Downloads/text.txt", "r")

lines = []

for line in file:
    cleaned_line = re.sub(r"\s+", "", line)
    #

I have txt file with something like this. L means Left, Right mean Right on the tree. Of course the real txt file contains much more records. My questions is: how to deal with that? How to add this values to the tree?

G RR
A
C L
F LLR
X LLL
F R
X RL
H LLG RR
C L
F LLR
X LLL
F R
X RL
H LL

Answer 1

I'm building the tree by going through the list and deciding on the L/R characters which way to go. When I found a non existing leaf, I create a Node there with the value of None. Multiple visits to the same leaf will overwrite the value, but you can easily change that. If the splitted text has only one value, that will be the root Node's value.

I added a printing method that will traverse the tree and print the root of the subtree, then the left and right leaves. It also indents it according to it's level.

class Node:
    def __init__(self, key):
        self.left = None
        self.right = None
        self.val = key

    def __str__(self):
        return "{}".format(self.val)

    def _printTree(self, node, level=0):
        if node != None:
            print(f"{'-'*level}{node}")
            self._printTree(node.left,level+1)
            self._printTree(node.right,level+1)

    def printTree(self):
        self._printTree(self)

p = s.split('\n')
root = Node(None)
for k in p:
    v = k.split()
    if len(v) == 1:
        root.val = v[0]
    else:
        r = root
        for c in v[1]:
            if c == 'L':
                if r.left is None:
                    r.left = Node(None)
                r = r.left
            elif c == 'R':
                if r.right is None:
                    r.right = Node(None)
                r = r.right
        r.val = v[0]

root.printTree()

Using the input text you wrote this is what gets generated:

A
-C
--H
---X
---F
-F
--X
--G