Question

1.) Write a recursive function named isPalindrome that will take a single string as an argument and determine if the argument is a palindrome. The function must return True if the argument is a palindrome, False otherwise. Recall that any string is a palindrome if its first and last characters are the same and the rest of it is also a palindrome (therefore, a single character is a palindrome):

2.) Consider a text file named samplestrings.txt that contains a collection of strings, one per line. Write a short Python program to read the entire file and display the percentage of strings in the file that are palindromes. Assume that the input file resides in the current working directory. Your code must include the following:

A call to the function you created in problem (1) to determine if a particular string is a palindrome.

A try-catch block to detect any file IOError exceptions. If an error is detected, your program should inform the user that an error occurred and exit.

Answer 1

def isPalindrome(s):

if len(s) <= 1:

return True

if s[0] != s[-1]:

return False

return isPalindrome(s[1:-1])

try:

f = open("samplestrings.txt")

words = f.read().split()

f.close()

palCount = 0

for word in words:

if isPalindrome(word):

palCount += 1

print("Percentage =", round(palCount*100/len(words), 2))

except:

print("Invalid file")

''' SAMPLE FILE

racecar

madam

HomeworkLib

india

dad

mom

SAMPLE OUTPUT

Percentage = 66.67

'''

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