import numpy as np
import matplotlib.pyplot as plt
import string, random, time

def randString(size=10, chars=string.ascii_uppercase):
    return ''.join(random.choice(chars) for _ in range(size))

def is_substring(a,b):
    found = False
    for x in range(len(b)):
        for i in range(len(a)):
            if x+i >= len(b):
                found = False
                break
            if a[i] == b[x+i]:
                found = True
            else:
                found = False
                break
        if found:
            break
    return found


def default_is_substring(a,b):
    return a in b

a = "CAT"

xvals = np.arange(0,100,10)

mine = []
theirs = []

for x in xvals:
    b = randString(x)

    starttime = time.time()
    is_substring(a,b)
    endtime = time.time()
    mine.append(endtime - starttime)

    starttime = time.time()
    default_is_substring(a,b)
    endtime = time.time()
    theirs.append(endtime - starttime)


plt.plot(xvals,mine)

plt.plot(xvals,theirs)


plt.grid()
plt.show()