Python/matrix/binary_search_matrix.py

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def binary_search(array: list, lower_bound: int, upper_bound: int, value: int) -> int:
"""
This function carries out Binary search on a 1d array and
return -1 if it do not exist
array: A 1d sorted array
value : the value meant to be searched
>>> matrix = [1, 4, 7, 11, 15]
>>> binary_search(matrix, 0, len(matrix) - 1, 1)
0
>>> binary_search(matrix, 0, len(matrix) - 1, 23)
-1
"""
r = int((lower_bound + upper_bound) // 2)
if array[r] == value:
return r
if lower_bound >= upper_bound:
return -1
if array[r] < value:
return binary_search(array, r + 1, upper_bound, value)
else:
return binary_search(array, lower_bound, r - 1, value)
def mat_bin_search(value: int, matrix: list) -> list:
"""
This function loops over a 2d matrix and calls binarySearch on
the selected 1d array and returns [-1, -1] is it do not exist
value : value meant to be searched
matrix = a sorted 2d matrix
>>> matrix = [[1, 4, 7, 11, 15],
... [2, 5, 8, 12, 19],
... [3, 6, 9, 16, 22],
... [10, 13, 14, 17, 24],
... [18, 21, 23, 26, 30]]
>>> target = 1
>>> mat_bin_search(target, matrix)
[0, 0]
>>> target = 34
>>> mat_bin_search(target, matrix)
[-1, -1]
"""
index = 0
if matrix[index][0] == value:
return [index, 0]
while index < len(matrix) and matrix[index][0] < value:
r = binary_search(matrix[index], 0, len(matrix[index]) - 1, value)
if r != -1:
return [index, r]
index += 1
return [-1, -1]
if __name__ == "__main__":
import doctest
doctest.testmod()