使用dfs遍历二叉树，在给定点停止(在Python中)

# 定义二叉树节点类
class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

# 使用DFS遍历二叉树，在给定点停止
def dfs(node, stop_val):
    if node is None:
        return
    
    # 在给定点停止
    if node.val == stop_val:
        return
    
    # 打印当前节点的值
    print(node.val)
    
    # 递归遍历左子树
    dfs(node.left, stop_val)
    
    # 递归遍历右子树
    dfs(node.right, stop_val)

# 创建二叉树
#        1
#       / \
#      2   3
#     / \   \
#    4   5   6
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
root.left.left = TreeNode(4)
root.left.right = TreeNode(5)
root.right.right = TreeNode(6)

# 在节点值为3的位置停止遍历
dfs(root, 3)

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