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Python

from typing import TypedDict # 定义数据类型
from langgraph.graph import StateGraph,END,START
# 1. 定义State(状态) -- 白板上只有一个字段"count"
class State(TypedDict):
count:int
# 2. 编写Node(节点) -- 两个"工人"
def node_a(state:State):
# 接收当前State状态,返回要更新的部分
print(f'[Node A]收到状态:{state}')
return {"count":state["count"]+1}
def node_b(state:State):
print(f'[Node B]收到状态:{state}')
return {"count":state["count"]+1}
# 3. 添加Node到图中
workflow = StateGraph(State) # 创建画布
workflow.add_node("A",node_a) # 添加节点A
workflow.add_node("B",node_b) # 添加节点B
# 4. 用Edge连线
workflow.add_edge(START,"A") # START -> A
workflow.add_edge("A","B") # A -> B
workflow.add_edge("B",END) # B -> END
# 编译成可运行应用
app = workflow.compile()
# 传入初始状态,执行工作流
print("---开始执行---")
result = app.invoke({"count":1})
print("最终状态:",result) # 输出{'count':4}
# 保存可视化架构图
with open('workflow.png', 'wb') as f:
f.write(app.get_graph().draw_mermaid_png())
print("图表已保存为 workflow.png")