使用递归获取所有树子项

class TreeNode:
    def __init__(self, value):
        self.value = value
        self.children = []

def get_all_subitems(node):
    if not node:
        return []
    
    result = [node.value]
    for child in node.children:
        result.extend(get_all_subitems(child))
    
    return result

# 示例用法
root = TreeNode('A')
root.children.append(TreeNode('B'))
root.children.append(TreeNode('C'))
root.children[0].children.append(TreeNode('D'))
root.children[0].children.append(TreeNode('E'))

print(get_all_subitems(root))  # 输出: ['A', 'B', 'D', 'E', 'C']

def get_all_subitems_iterative(root):
    if not root:
        return []
    
    stack = [root]
    result = []
    
    while stack:
        node = stack.pop()
        result.append(node.value)
        for child in reversed(node.children):  # 反转顺序以保持原始顺序
            stack.append(child)
    
    return result

# 示例用法
print(get_all_subitems_iterative(root))  # 输出: ['A', 'B', 'D', 'E', 'C']