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