Solution Exercise 37: python algorithm which determines the list of numbers containing the digit 3

Exercise 37

Write a python algorithm that extracts from a given list of numbers the sublist made up of numbers that contain the digit 3.

Solution

# method which tests whether or not a number contains the digit 3
def contains3 (n):
     # convert n to string
     s = str (n)
     if '3' in s:
          return True
     else:
          return False
    
# method that determines the list of numbers that contain the digit 3

def listContains3 (L):
     # initialization of the list of numbers that contain the digit 3
     list3 = []
     for n in L:
          if contains3 (n):
               list3.append (n)
     return list3
    
# Example
L = [21, 137, 25, 31, 71, 239]
print (listContains3 (L)) # print [137, 31, 239]