解析小票条目并计算合计

def solve():
    from pyodide.http import open_url
    from io import StringIO
    import pandas as pd
    items = pd.read_csv(StringIO(open_url("https://data.zuihe.com/dbd/ms-ledger/state_01/receipt_items.csv").read()))
    print(f"Total items: {len(items)}")
    by_rcp = items.groupby('receipt_id').agg(count=('item_id','count'),total=('subtotal','sum')).reset_index()
    by_rcp['total'] = by_rcp['total'].round(2)
    print(f"Receipts with items: {len(by_rcp)}")
    print(f"Avg items/receipt: {round(by_rcp['count'].mean(),1)}")
    for _, row in by_rcp.head(5).iterrows():
        print(f"  {row['receipt_id']}: {row['count']} items total={row['total']}")