如何从平面数组构建树形结构

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

def build_tree_from_array(array):
    node_dict = {}
    root = None

    for item in array:
        node_id = item['id']
        node_value = item['value']
        parent_id = item['parent_id']

        node = TreeNode(node_value)
        node_dict[node_id] = node

        if parent_id is None:
            root = node
        else:
            parent_node = node_dict[parent_id]
            parent_node.children.append(node)

    return root

# 示例数组
array = [
    {'id': 1, 'value': 'A', 'parent_id': None},
    {'id': 2, 'value': 'B', 'parent_id': 1},
    {'id': 3, 'value': 'C', 'parent_id': 1},
    {'id': 4, 'value': 'D', 'parent_id': 2},
    {'id': 5, 'value': 'E', 'parent_id': 2},
    {'id': 6, 'value': 'F', 'parent_id': 3},
]

# 构建树形结构
tree = build_tree_from_array(array)

# 打印树形结构
def print_tree(node, level=0):
    print('  ' * level + node.value)
    for child in node.children:
        print_tree(child, level + 1)

print_tree(tree)

A
  B
    D
    E
  C
    F