palindrome.py

import matplotlib.pyplot as plt
%matplotlib inline
from tqdm import trange

def isPalindrome(x):
  return str(x) == str(x)[::-1]


def graph_number_to_iterations():
  lychrel = [196,295,394,493,592,689,691,788,790,879,887,978,
  986,1495,1497,1585,1587,1675,1677,1765,1767,1855,
  1857,1945,1947,1997,2494,2496,2584,2586,2674,2676,
  2764,2766,2854,2856,2944,2946,2996,3493,3495,3583,
  3585,3673,3675]

  iters=[]
  iter = 0

  for x in trange(1000):
    iter = 0
    while not isPalindrome(x) and x not in lychrel:
      iter+=1
      x = int(x) + int(str(x)[::-1])
    iters.append(iter)

  x_axis = [i for i in range(1000)]
  plt.plot(x_axis, iters, 'b.')
  plt.xlabel('Numbers')
  plt.ylabel('Number of iterations until palindrome')

def graph_digits_to_iterations():
  x_axis2 = []
  x = 196
  for iter in trange(100000):
    x = int(x) + int(str(x)[::-1])
    x_axis2.append(len(str(x)))

  plt.plot(x_axis2, [i for i in range(100000)], 'r.')
  plt.xlabel('Number of digits')
  plt.ylabel('Number of iterations')

if __name__ == '__main__':
  graph_number_to_iterations()
  # graph_digits_to_iterations()