sum_sub.py

from matplotlib import pyplot as plt
import random

N = 10000
n = 100
L = list()
tL = list()

v = 0
for i in range(N):
    r = random.random()
    v += r
    if v >= 1.0:
        v -= 1.0
    L.append(int(n*r))
    tL.append(int(n*v))

plt.hist(L,n,alpha=0.5,color='r')
plt.hist(tL,n,alpha=0.5,color='b')
plt.savefig('example.png')