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python - 带有搜索和删除功能的python二叉树遍历

问题描述

我创建了一个二叉树遍历项目。不幸的是，我对python有基本的了解。我正确地写了“preorder”、“inorder”和“postorder”。但我无法创建查找和删除节点功能。请帮忙。请检查下面的代码。请帮助创建这两个功能。谢谢

    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None
    def find(self, value):
        if self.value == value:
            return True
        elif value < self.value and self.left:
            return self.left.find(value)
        elif value > self.value and self.right:
            return self.right.find(value)
        return False
class BinaryTree(object):
    def __init__(self, root):
        self.root = Node(root)
    def print_tree(self, traversal_type):
        if traversal_type == "preorder":
            return self.preorder_print(tree.root, "")
        elif traversal_type == "inorder":
            return self.inorder_print(tree.root, "")
        elif traversal_type == "postorder":
            return self.postorder_print(tree.root, "")
        else:
            print("Traversal type "+str(traversal_type)+" is not supported.")
    def preorder_print(self, start, traversal):
        # Root->Left->Right
        if start:
            traversal += (str(start.value)+"-")
            traversal = self.preorder_print(start.left, traversal)
            traversal = self.preorder_print(start.right, traversal)
        return traversal
    def inorder_print(self, start, traversal):
        # Left->Root->Right
        if start:
            traversal = self.inorder_print(start.left, traversal)
            traversal += (str(start.value) + "-")
            traversal = self.inorder_print(start.right, traversal)
        return traversal
    def postorder_print(self, start, traversal):
        # Left->Right->Root
        if start:
            traversal = self.postorder_print(start.left, traversal)
            traversal = self.postorder_print(start.right, traversal)
            traversal += (str(start.value) + "-")
        return traversal
        # Set up tree order
tree = BinaryTree(1)
tree.root.left = Node(2)
tree.root.right = Node(3)
tree.root.left.left = Node(4)
tree.root.left.right = Node(5)
tree.root.right.left = Node(6)
tree.root.right.right = Node(7)
print("Preorder: " + tree.print_tree("preorder"))    # 1-2-4-5-3-6-7
print("Inorder: " + tree.print_tree("inorder"))      # 4-2-5-1-6-3-7
print("Postorder: " + tree.print_tree("postorder"))  # 4-2-5-6-3-7-1
print(tree.root.find(1))
print(tree.root.find(2))
print(tree.root.find(3))
print(tree.root.find(4))
print(tree.root.find(5))
print(tree.root.find(6))
print(tree.root.find(7))
print(tree.root.find(8)) ```

标签： pythonbinary-tree

解决方案

find 不起作用的原因是您设置的树不是二叉搜索树。在 BST 中，左侧的所有节点的值都低于根，而右侧的所有节点的值都更高。检查您构建的树。

这是删除节点的实现。

https://www.geeksforgeeks.org/binary-search-tree-set-2-delete/

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