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adding a matrix equalization algorithm #11360

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May 1, 2024
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55 changes: 55 additions & 0 deletions matrix/matrix_equalization.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,55 @@
from sys import maxsize


def array_equalization(vector: list[int], step_size: int) -> int:
"""
This algorithm equalizes all elements of the input vector
to a common value, by making the minimal number of
"updates" under the constraint of a step size (step_size).

>>> array_equalization([1, 1, 6, 2, 4, 6, 5, 1, 7, 2, 2, 1, 7, 2, 2], 4)
4
>>> array_equalization([22, 81, 88, 71, 22, 81, 632, 81, 81, 22, 92], 2)
5
>>> array_equalization([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 5)
0
>>> array_equalization([22, 22, 22, 33, 33, 33], 2)
2
>>> array_equalization([1, 2, 3], 0)
Traceback (most recent call last):
ValueError: Step size must be positive and non-zero.
>>> array_equalization([1, 2, 3], -1)
Traceback (most recent call last):
ValueError: Step size must be positive and non-zero.
>>> array_equalization([1, 2, 3], 0.5)
Traceback (most recent call last):
ValueError: Step size must be an integer.
>>> array_equalization([1, 2, 3], maxsize)
1
"""
if step_size <= 0:
raise ValueError("Step size must be positive and non-zero.")
if not isinstance(step_size, int):
raise ValueError("Step size must be an integer.")

unique_elements = set(vector)
min_updates = maxsize

for element in unique_elements:
elem_index = 0
updates = 0
while elem_index < len(vector):
if vector[elem_index] != element:
updates += 1
elem_index += step_size
else:
elem_index += 1
min_updates = min(min_updates, updates)

return min_updates


if __name__ == "__main__":
from doctest import testmod

testmod()