从多个ParentNodes中检索多个ChildNodes

from collections import deque

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

def bfs_retrieve(parent_nodes, target_value):
    queue = deque(parent_nodes)
    while queue:
        current_node = queue.popleft()
        if current_node.value == target_value:
            return current_node
        for child in current_node.children:
            queue.append(child)
    return None

def dfs_retrieve(parent_nodes, target_value):
    for node in parent_nodes:
        if node.value == target_value:
            return node
        for child in node.children:
            result = dfs_retrieve([child], target_value)
            if result:
                return result
    return None

def bfs_retrieve_safe(parent_nodes, target_value):
    queue = deque(parent_nodes)
    visited = set()
    while queue:
        current_node = queue.popleft()
        if current_node in visited:
            continue
        visited.add(current_node)
        if current_node.value == target_value:
            return current_node
        for child in current_node.children:
            queue.append(child)
    return None

class IndexedTree:
    def __init__(self):
        self.nodes = {}
    
    def add_node(self, node):
        self.nodes[node.value] = node
    
    def retrieve_node(self, value):
        return self.nodes.get(value, None)

# Example usage
tree = IndexedTree()
root = TreeNode('root')
child1 = TreeNode('child1')
child2 = TreeNode('child2')
root.children.append(child1)
root.children.append(child2)
tree.add_node(root)
tree.add_node(child1)
tree.add_node(child2)

retrieved_node = tree.retrieve_node('child1')