Python/searches/double_linear_search_recursion.py
Du Yuanchao dc415ec14a
Added double linear search recursion (#2445)
* double linear search recursion

* fixup! Format Python code with psf/black push

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
2020-09-18 09:55:02 +02:00

36 lines
911 B
Python

def search(list_data: list, key: int, left: int = 0, right: int = 0) -> int:
"""
Iterate through the array to find the index of key using recursion.
:param list_data: the list to be searched
:param key: the key to be searched
:param left: the index of first element
:param right: the index of last element
:return: the index of key value if found, -1 otherwise.
>>> search(list(range(0, 11)), 5)
5
>>> search([1, 2, 4, 5, 3], 4)
2
>>> search([1, 2, 4, 5, 3], 6)
-1
>>> search([5], 5)
0
>>> search([], 1)
-1
"""
right = right or len(list_data) - 1
if left > right:
return -1
elif list_data[left] == key:
return left
elif list_data[right] == key:
return right
else:
return search(list_data, key, left + 1, right - 1)
if __name__ == "__main__":
import doctest
doctest.testmod()