相关系数

def solve(____):
    import math
    n = len(____)
    mean_a = sum(____) / n
    mean_b = sum(____) / n
    cov = sum((____) * (____) for a, b in zip(____)) / n
    var_a = sum((____) ** ____ for a in returns_a) / n
    var_b = sum((____) ** ____ for b in returns_b) / n
    corr = cov / (math.sqrt(____) * math.sqrt(____))
    return {"____": round(____), "____": round(____)}