mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-24 05:21:09 +00:00
cfbbfd9896
* refactor: Merge and add benchmarks to palindrome
* updating DIRECTORY.md
* chore: Fix failing tests
* Update strings/palindrome.py
Co-authored-by: Christian Clauss <cclauss@me.com>
* Update palindrome.py
---------
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>
105 lines
2.9 KiB
Python
105 lines
2.9 KiB
Python
# Algorithms to determine if a string is palindrome
|
|
|
|
from timeit import timeit
|
|
|
|
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_traversal(s: str) -> bool:
|
|
"""
|
|
Return True if s is a palindrome otherwise return False.
|
|
|
|
>>> all(is_palindrome_traversal(key) is value for key, value in test_data.items())
|
|
True
|
|
"""
|
|
end = len(s) // 2
|
|
n = len(s)
|
|
|
|
# We need to traverse till half of the length of string
|
|
# as we can get access of the i'th last element from
|
|
# i'th index.
|
|
# eg: [0,1,2,3,4,5] => 4th index can be accessed
|
|
# with the help of 1st index (i==n-i-1)
|
|
# where n is length of string
|
|
return all(s[i] == s[n - i - 1] for i in range(end))
|
|
|
|
|
|
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) <= 2:
|
|
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]
|
|
|
|
|
|
def benchmark_function(name: str) -> None:
|
|
stmt = f"all({name}(key) is value for key, value in test_data.items())"
|
|
setup = f"from __main__ import test_data, {name}"
|
|
number = 500000
|
|
result = timeit(stmt=stmt, setup=setup, number=number)
|
|
print(f"{name:<35} finished {number:,} runs in {result:.5f} seconds")
|
|
|
|
|
|
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")
|
|
|
|
# finished 500,000 runs in 0.46793 seconds
|
|
benchmark_function("is_palindrome_slice")
|
|
# finished 500,000 runs in 0.85234 seconds
|
|
benchmark_function("is_palindrome")
|
|
# finished 500,000 runs in 1.32028 seconds
|
|
benchmark_function("is_palindrome_recursive")
|
|
# finished 500,000 runs in 2.08679 seconds
|
|
benchmark_function("is_palindrome_traversal")
|