二叉树DFS/BFS遍历

from queue import Queue


class BinaryTree:
    def __init__(self, value):
        self.value = value
        self.left_child = None
        self.right_child = None
    
    def insert_left(self, value):
        if self.left_child == None:
            self.left_child = BinaryTree(value)
        else:
            new_node = BinaryTree(value)
            new_node.left_child = self.left_child
            self.left_child = new_node

    def insert_right(self, value):
        if self.right_child == None:
            self.right_child = BinaryTree(value)
        else:
            new_node = BinaryTree(value)
            new_node.right_child = self.right_child
            self.right_child = new_node
        
    def pre_order(self):
        print(self.value)
        if self.left_child:
            self.left_child.pre_order()
        
        if self.right_child:
            self.right_child.pre_order()

    def in_order(self):
        if self.left_child:
            self.left_child.in_order()
        print(self.value)
        if self.right_child:
            self.right_child.in_order()
    
    def post_order(self):
        if self.left_child:
            self.left_child.post_order()
        
        if self.right_child:
            self.right_child.post_order()

        print(self.value)

    def bfs(self):
        queue = Queue()
        queue.put(self)

        while not queue.empty():
            current_node = queue.get()        
            print(current_node.value)
            if current_node.left_child:
                queue.put(current_node.left_child)
            
            if current_node.right_child:
                queue.put(current_node.right_child)
        



a_node = BinaryTree('a')
a_node.insert_left('b')
a_node.insert_right('c')

b_node = a_node.left_child
b_node.insert_right('d')

d_node = b_node.right_child

c_node = a_node.right_child
c_node.insert_left('e')
c_node.insert_right('f')

e_node = c_node.left_child
f_node = c_node.right_child

print(a_node.value, b_node.value, c_node.value, d_node.value, e_node.value, f_node.value)

a_node.pre_order()
a_node.in_order()  # b d a e c f
a_node.post_order()  # dbefca

a_node.bfs()