mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-27 15:01:08 +00:00
78 lines
2.3 KiB
Python
78 lines
2.3 KiB
Python
"""
|
|
This is pure Python implementation of linear search algorithm
|
|
|
|
For doctests run following command:
|
|
python3 -m doctest -v linear_search.py
|
|
|
|
For manual testing run:
|
|
python3 linear_search.py
|
|
"""
|
|
|
|
|
|
def linear_search(sequence: list, target: int) -> int:
|
|
"""A pure Python implementation of a linear search algorithm
|
|
|
|
:param sequence: a collection with comparable items (as sorted items not required
|
|
in Linear Search)
|
|
:param target: item value to search
|
|
:return: index of found item or -1 if item is not found
|
|
|
|
Examples:
|
|
>>> linear_search([0, 5, 7, 10, 15], 0)
|
|
0
|
|
>>> linear_search([0, 5, 7, 10, 15], 15)
|
|
4
|
|
>>> linear_search([0, 5, 7, 10, 15], 5)
|
|
1
|
|
>>> linear_search([0, 5, 7, 10, 15], 6)
|
|
-1
|
|
"""
|
|
for index, item in enumerate(sequence):
|
|
if item == target:
|
|
return index
|
|
return -1
|
|
|
|
|
|
def rec_linear_search(sequence: list, low: int, high: int, target: int) -> int:
|
|
"""
|
|
A pure Python implementation of a recursive linear search algorithm
|
|
|
|
:param sequence: a collection with comparable items (as sorted items not required
|
|
in Linear Search)
|
|
:param low: Lower bound of the array
|
|
:param high: Higher bound of the array
|
|
:param target: The element to be found
|
|
:return: Index of the key or -1 if key not found
|
|
|
|
Examples:
|
|
>>> rec_linear_search([0, 30, 500, 100, 700], 0, 4, 0)
|
|
0
|
|
>>> rec_linear_search([0, 30, 500, 100, 700], 0, 4, 700)
|
|
4
|
|
>>> rec_linear_search([0, 30, 500, 100, 700], 0, 4, 30)
|
|
1
|
|
>>> rec_linear_search([0, 30, 500, 100, 700], 0, 4, -6)
|
|
-1
|
|
"""
|
|
if not (0 <= high < len(sequence) and 0 <= low < len(sequence)):
|
|
raise Exception("Invalid upper or lower bound!")
|
|
if high < low:
|
|
return -1
|
|
if sequence[low] == target:
|
|
return low
|
|
if sequence[high] == target:
|
|
return high
|
|
return rec_linear_search(sequence, low + 1, high - 1, target)
|
|
|
|
|
|
if __name__ == "__main__":
|
|
user_input = input("Enter numbers separated by comma:\n").strip()
|
|
sequence = [int(item.strip()) for item in user_input.split(",")]
|
|
|
|
target = int(input("Enter a single number to be found in the list:\n").strip())
|
|
result = linear_search(sequence, target)
|
|
if result != -1:
|
|
print(f"linear_search({sequence}, {target}) = {result}")
|
|
else:
|
|
print(f"{target} was not found in {sequence}")
|