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https://github.com/autistic-symposium/master-algorithms-py.git
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71 lines
1.7 KiB
Python
71 lines
1.7 KiB
Python
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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# author: bt3gl
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def binary_search_recursive(array, item, higher=None, lower=0):
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higher = higher or len(array)
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if higher < lower:
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return False
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mid = (higher + lower)//2
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if item == array[mid]:
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return mid
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elif item < array[mid]:
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return binary_search_recursive(array, item, higher=mid-1, lower=lower)
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else:
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return binary_search_recursive(array, item, higher=higher, lower=mid+1)
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def binary_search_iterative(array, item):
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lower, higher = 0, len(array)
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while lower < higher:
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mid = (higher+lower)//2
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if array[mid] == item:
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return mid
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elif array[mid] > item:
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higher = mid
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else:
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lower=mid+1
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return False
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def binary_search_matrix(matrix, item, lower=0, higher=None):
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""" Binary search in a matrix """
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if not matrix:
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return None
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rows = len(matrix)
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cols = len(matrix[0])
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higher = higher or rows*cols
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if higher > lower:
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mid = (higher + lower)//2
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row = mid//cols
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col = mid%cols
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item = matrix[row][col]
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if item == item:
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return row, col
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elif item < item:
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return binary_search_matrix(matrix, item, lower, mid-1)
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else:
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return binary_search_matrix(matrix, item, mid+1, higher)
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return None
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if __name__ == '__main__':
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array = [2, 3, 5, 6, 8, 10, 15, 23]
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matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
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item = 15
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print('Recursive: ', binary_search_recursive(array, item))
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print('Iterative: ', binary_search_iterative(array, item))
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print('Matrix: ', binary_search_matrix(matrix, item))
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