价格上限分析

def solve(____):
    if ceiling_price >= equilibrium_price:
        return {"____": ceiling_price, "____": equilibrium_price, "____": "____"}
    a, b = demand_func
    c, d = supply_func
    qd = a - b * ceiling_price
    qs = c + d * ceiling_price
    shortage = qd - qs
    return {"____": ceiling_price, "____": qd, "____": qs, "____": shortage}