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45 lines
1.3 KiB
Python
45 lines
1.3 KiB
Python
def is_palindrome(s: str) -> bool:
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"""
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Determine if the string s is a palindrome.
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>>> is_palindrome("A man, A plan, A canal -- Panama!")
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True
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>>> is_palindrome("Hello")
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False
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>>> is_palindrome("Able was I ere I saw Elba")
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True
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>>> is_palindrome("racecar")
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True
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>>> is_palindrome("Mr. Owl ate my metal worm?")
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True
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"""
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# Since punctuation, capitalization, and spaces are often ignored while checking
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# palindromes, we first remove them from our string.
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s = "".join(character for character in s.lower() if character.isalnum())
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# return s == s[::-1] the slicing method
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# uses extra spaces we can
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# better with iteration method.
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end = len(s) // 2
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n = len(s)
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# We need to traverse till half of the length of string
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# as we can get access of the i'th last element from
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# i'th index.
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# eg: [0,1,2,3,4,5] => 4th index can be accessed
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# with the help of 1st index (i==n-i-1)
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# where n is length of string
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for i in range(end):
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if s[i] != s[n - i - 1]:
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return False
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return True
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if __name__ == "__main__":
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s = input("Please enter a string to see if it is a palindrome: ")
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if is_palindrome(s):
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print(f"'{s}' is a palindrome.")
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else:
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print(f"'{s}' is not a palindrome.")
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