[刷题] 求素数

t = time()
    p_list = []
    for i in range(2, b):
        flag = True
        for p in p_list:
            if p > math.sqrt(i):
                break
            if i % p == 0:
                flag = False
                break
        if flag:
            p_list.append(i)
    print(time() - t)
    print(p_list)

def is_prime3(x):
    flag = True
    for p in p_list2:
        if p > math.sqrt(x):
            break
        if x % p == 0:
            flag = False
            break
    if flag:
        p_list2.append(x)
    return flag

p_list2 = []
t = time()
list(filter(is_prime3, list(range(2, b))))
print(time() - t)
print(p_list2)

 1 import numpy as np
 2 import matplotlib as mpl
 3 import matplotlib.pyplot as plt
 4 
 5 
 6 def clip(x, path):
 7     for i in range(len(x)):
 8         if x[i] >= path:
 9             x[i] %= path
10 
11 
12 if __name__ == "__main__":
13     mpl.rcParams[‘font.sans-serif‘] = [‘SimHei‘] #中文字体
14     mpl.rcParams[‘axes.unicode_minus‘] = False
15 
16     path = 5000     # 环形公路的长度
17     n = 100         # 公路中的车辆数目
18     v0 = 50          # 车辆的初始速度
19     p = 0.3         # 随机减速概率
20     Times = 3000
21 
22     np.random.seed(0)
23     x = np.random.rand(n) * path
24     x.sort()
25     v = np.tile([v0], n).astype(np.float)
26 
27     plt.figure(figsize=(9, 7), facecolor=‘w‘)
28     for t in range(Times):
29         plt.scatter(x, [t]*n, s=1, c=‘k‘, alpha=0.05)
30         for i in range(n):
31             if x[(i+1)%n] > x[i]:
32                 d = x[(i+1) % n] - x[i]   # 距离前车的距离
33             else:
34                 d = path - x[i] + x[(i+1) % n]
35             if v[i] < d:
36                 if np.random.rand() > p:   #随机减速
37                     v[i] += 1
38                 else:
39                     v[i] -= 1
40             else:
41                 v[i] = d - 1
42         v = v.clip(0, 150)
43         x += v
44         clip(x, path)
45     plt.xlim(0, path)
46     plt.ylim(0, Times)
47     plt.xlabel(‘车辆位置‘, fontsize=14)
48     plt.ylabel(‘模拟时间‘, fontsize=14)
49     plt.title(‘环形公路车辆堵车模拟‘, fontsize=18)
50     plt.tight_layout(pad=2)
51     plt.show()