import random
import matplotlib.pyplot as plt
import numpy as np


def p(x):
	return 6 * (1 - x) * x if 0 < x < 1 else 0


random.seed(12345)
S = []
x = 0.5
T = 200000
sigma = 0.1
rej = 0
for t in range(T):
	xp = x + random.gauss(0, sigma)
	px = p(x)
	pxp = p(xp)
	if px < pxp or px * random.uniform(0, 1) <= pxp:
		x = xp
	else:
		rej += 1
	S.append(x)

x = np.linspace(0, 1, 1000)
y = [p(e) for e in x]
plt.hist(S, bins=40, density=True)
plt.plot(x, y)
plt.show()