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* ci(pre-commit): Add pep8-naming to `pre-commit` hooks (#7038) * refactor: Fix naming conventions (#7038) * Update arithmetic_analysis/lu_decomposition.py Co-authored-by: Christian Clauss <cclauss@me.com> * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * refactor(lu_decomposition): Replace `NDArray` with `ArrayLike` (#7038) * chore: Fix naming conventions in doctests (#7038) * fix: Temporarily disable project euler problem 104 (#7069) * chore: Fix naming conventions in doctests (#7038) Co-authored-by: Christian Clauss <cclauss@me.com> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
116 lines
3.9 KiB
Python
116 lines
3.9 KiB
Python
# Created by susmith98
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from collections import Counter
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from timeit import timeit
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# Problem Description:
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# Check if characters of the given string can be rearranged to form a palindrome.
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# Counter is faster for long strings and non-Counter is faster for short strings.
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def can_string_be_rearranged_as_palindrome_counter(
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input_str: str = "",
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) -> bool:
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"""
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A Palindrome is a String that reads the same forward as it does backwards.
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Examples of Palindromes mom, dad, malayalam
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>>> can_string_be_rearranged_as_palindrome_counter("Momo")
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True
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>>> can_string_be_rearranged_as_palindrome_counter("Mother")
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False
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>>> can_string_be_rearranged_as_palindrome_counter("Father")
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False
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>>> can_string_be_rearranged_as_palindrome_counter("A man a plan a canal Panama")
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True
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"""
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return sum(c % 2 for c in Counter(input_str.replace(" ", "").lower()).values()) < 2
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def can_string_be_rearranged_as_palindrome(input_str: str = "") -> bool:
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"""
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A Palindrome is a String that reads the same forward as it does backwards.
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Examples of Palindromes mom, dad, malayalam
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>>> can_string_be_rearranged_as_palindrome("Momo")
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True
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>>> can_string_be_rearranged_as_palindrome("Mother")
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False
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>>> can_string_be_rearranged_as_palindrome("Father")
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False
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>>> can_string_be_rearranged_as_palindrome_counter("A man a plan a canal Panama")
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True
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"""
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if len(input_str) == 0:
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return True
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lower_case_input_str = input_str.replace(" ", "").lower()
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# character_freq_dict: Stores the frequency of every character in the input string
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character_freq_dict: dict[str, int] = {}
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for character in lower_case_input_str:
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character_freq_dict[character] = character_freq_dict.get(character, 0) + 1
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"""
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Above line of code is equivalent to:
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1) Getting the frequency of current character till previous index
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>>> character_freq = character_freq_dict.get(character, 0)
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2) Incrementing the frequency of current character by 1
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>>> character_freq = character_freq + 1
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3) Updating the frequency of current character
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>>> character_freq_dict[character] = character_freq
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"""
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"""
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OBSERVATIONS:
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Even length palindrome
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-> Every character appears even no.of times.
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Odd length palindrome
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-> Every character appears even no.of times except for one character.
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LOGIC:
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Step 1: We'll count number of characters that appear odd number of times i.e oddChar
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Step 2:If we find more than 1 character that appears odd number of times,
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It is not possible to rearrange as a palindrome
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"""
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odd_char = 0
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for character_count in character_freq_dict.values():
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if character_count % 2:
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odd_char += 1
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if odd_char > 1:
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return False
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return True
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def benchmark(input_str: str = "") -> None:
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"""
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Benchmark code for comparing above 2 functions
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"""
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print("\nFor string = ", input_str, ":")
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print(
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"> can_string_be_rearranged_as_palindrome_counter()",
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"\tans =",
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can_string_be_rearranged_as_palindrome_counter(input_str),
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"\ttime =",
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timeit(
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"z.can_string_be_rearranged_as_palindrome_counter(z.check_str)",
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setup="import __main__ as z",
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),
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"seconds",
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)
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print(
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"> can_string_be_rearranged_as_palindrome()",
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"\tans =",
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can_string_be_rearranged_as_palindrome(input_str),
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"\ttime =",
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timeit(
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"z.can_string_be_rearranged_as_palindrome(z.check_str)",
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setup="import __main__ as z",
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),
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"seconds",
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)
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if __name__ == "__main__":
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check_str = input(
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"Enter string to determine if it can be rearranged as a palindrome or not: "
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).strip()
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benchmark(check_str)
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status = can_string_be_rearranged_as_palindrome_counter(check_str)
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print(f"{check_str} can {'' if status else 'not '}be rearranged as a palindrome")
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