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# Algorithms to determine if a string is palindrome

test_data = {

"MALAYALAM": True,

"String": False,

"rotor": True,

"level": True,

"A": True,

"BB": True,

"ABC": False,

"amanaplanacanalpanama": True, # "a man a plan a canal panama"

}

# Ensure our test data is valid

assert all((key == key[::-1]) is value for key, value in test_data.items())

def is_palindrome(s: str) -> bool:

"""

Return True if s is a palindrome otherwise return False.

>>> all(is_palindrome(key) is value for key, value in test_data.items())

True

"""

start_i = 0

end_i = len(s) - 1

while start_i < end_i:

if s[start_i] == s[end_i]:

start_i += 1

end_i -= 1

else:

return False

return True

def is_palindrome_recursive(s: str) -> bool:

"""

Return True if s is a palindrome otherwise return False.

>>> all(is_palindrome_recursive(key) is value for key, value in test_data.items())

True

"""

if len(s) <= 1:

return True

if s[0] == s[len(s) - 1]:

return is_palindrome_recursive(s[1:-1])

else:

return False

def is_palindrome_slice(s: str) -> bool:

"""

Return True if s is a palindrome otherwise return False.

>>> all(is_palindrome_slice(key) is value for key, value in test_data.items())

True

"""

return s == s[::-1]

if __name__ == "__main__":

for key, value in test_data.items():

assert is_palindrome(key) is is_palindrome_recursive(key)

assert is_palindrome(key) is is_palindrome_slice(key)

print(f"{key:21} {value}")

print("a man a plan a canal panama")

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