二进制搜索树删除方法不起作用

如何解决二进制搜索树删除方法不起作用

这是我尝试实现的BST，但是remove方法不会删除具有给定值的节点。 我尝试过这种方式：

1. 首先检查当前节点（我要删除的节点）是否有合适的孩子。

1.1）如果没有，那么我将当前节点替换为其左子节点。

1.2）并且如果当前节点有一个右孩子，则检查当前节点的右孩子是否有一个左孩子

1.2.1）如果右子节点有左子节点，则将当前节点替换为大于当前节点的最小节点，并替换为右子树中的最左侧节点

1.2.2）如果没有，则用其正确的子代替换当前节点。 但是该代码不会删除所选节点。我在哪里弄错了？

class BinarySearchTree:
    def __init__(self):
        self.root = None
    def insert(self,value):
        node = {'value':value,'left':None,'right':None}
        if self.root == None:
            self.root = node 
        else:
            
            current = self.root
            while True:
                if value > current['value']:
                    if current['right'] == None:
                        current['right'] = node
                        break
                    else:
                        current = current['right']
                else:
                    if current['left'] == None:
                        current['left'] = node
                        break
                    else:
                        current = current['left']
    def lookup(self,value):
        if self.root == None:
            return
        else:
            current = self.root
            while True:
                if value > current['value']:
                    if current['right'] == None:
                        return None
                    current = current['right']
                elif value < current['value']:
                    if current['left'] == None:
                        return None
                    current = current['left']
                else:
                    return current

    def remove(self,value):

        if not self.root:
            return False
        parent = None
        current = self.root
        while current:
            if value < current['value']:
                parent = current
                current = current['left']
            elif value > current['value']:
                parent = current
                current = current['right']
            elif value == current['value']:

                # 1)no right child
                if current['right'] == None:
                    if parent == None:
                        self.root = current['left']
                    else:
                        if current['value'] < parent['value']:
                            parent['left'] = current['left']
                        elif current['value'] > parent['value']:
                            parent['right'] = current['left']
                # 2) right child that doesnt have a left child
                elif current['right']['left'] == None:
                    current['right']['left'] = current['left']
                    if parent == None:
                        self.root= current['right']
                    else:
                        if parent['value'] > current['value']:
                            parent['left'] = current['right']
                        elif parent['value'] < current['value']:
                            parent['right'] = current['right']
                # 3)Right child that has a left child
                else:
                    #finding the right child's leftmost child
                    leftmost = current['right']['left']
                    leftmostParent = current['right']
                    while leftmost['left'] != None:
                        leftmostParent = leftmost
                        leftmost = leftmost['left']
                    leftmostParent['left'] = leftmost['right']
                    leftmost['left'] = current['left']
                    leftmost['right'] = current['right']

                    if parent == None:
                        self.root = leftmost
                    else:
                        if current['value'] < parent['value']:
                            parent['left'] = leftmost
                        elif current['value'] > parent['value']:
                            parent['right'] = leftmost
            return True   
                
    def get(self):
        my_bst = {
            'root':self.root,}
        return my_bst
        
      

bst = BinarySearchTree()
bst.insert(9)
bst.insert(4)
bst.insert(6)
bst.insert(20)
bst.insert(170)
bst.insert(15)
bst.insert(1)
bst.insert(150)
print(bst.remove(150))
print(bst.get())

解决方法

您的while current:循环实际上永远不会循环，因为您return True在循环结束时。我认为向右缩进return True可以解决问题。