自相关函数

def solve():
    import matplotlib
    matplotlib.use(____)
    import matplotlib.pyplot as plt
    import numpy as np
    from statsmodels.graphics.tsaplots import plot_acf
    from statsmodels.tsa.stattools import acf
    np.random.seed(____)
    y = np.cumsum(np.random.randn(____))
    fig, ax = plt.subplots(figsize=(____, ____))
    plot_acf(____)
    plt.tight_layout()
    plt.show()
    acf_vals = acf(____)
    print(____)