投资组合选择

def solve(____):
    excess_return = risky_return - risk_free_rate
    optimal_weight = excess_return / (____)
    optimal_weight = max(____, min(____, optimal_weight))
    risky_investment = wealth * optimal_weight
    risk_free_investment = wealth * (____ - optimal_weight)
    expected_return = risk_free_rate + optimal_weight * excess_return
    portfolio_std = optimal_weight * risky_std
    return {"____": round(____), "____": round(____), "____": round(____), "____": round(____), "____": round(____)}