二叉树向量重复值打印输出

class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

def find_duplicate_values(root):
    if not root:
        return
    
    visited = set()
    stack = [root]
    
    while stack:
        node = stack.pop()
        
        if node.val in visited:
            print(node.val)  # 打印重复值
            
        visited.add(node.val)
        
        if node.right:
            stack.append(node.right)
        if node.left:
            stack.append(node.left)

# 构建一个二叉树作为示例
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
root.left.left = TreeNode(2)
root.right.left = TreeNode(2)
root.right.right = TreeNode(4)

find_duplicate_values(root)