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Update binary_search.py

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marina 2023-07-31 14:58:10 -07:00 committed by GitHub
parent afdff04a69
commit 2396654457
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1 changed files with 19 additions and 12 deletions
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searching/binary_search.py
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@ -6,54 +6,61 @@
def binary_search_recursive(array, item, higher=None, lower=0): def binary_search_recursive(array, item, higher=None, lower=0):
higher = higher or len(array) higher = higher or len(array)
if higher < lower: if higher < lower:
return False return False
mid = (higher + lower)//2 mid = (higher + lower) // 2
if item == array[mid]: if item == array[mid]:
return mid return mid
elif item < array[mid]: elif item < array[mid]:
return binary_search_recursive(array, item, higher=mid-1, lower=lower) return binary_search_recursive(array, item, mid - 1, lower)
else: else:
return binary_search_recursive(array, item, higher=higher, lower=mid+1) return binary_search_recursive(array, item, =higher, mid + 1)
def binary_search_iterative(array, item): def binary_search_iterative(array, item):
lower, higher = 0, len(array) lower, higher = 0, len(array)
while lower < higher: while lower < higher:
mid = (higher+lower)//2 mid = (highe r+ lower) // 2
if array[mid] == item: if array[mid] == item:
return mid return mid
elif array[mid] > item: elif array[mid] > item:
higher = mid higher = mid
else: else:
lower=mid+1 lower = mid + 1
return False return False
def binary_search_matrix(matrix, item, lower=0, higher=None): def binary_search_matrix(matrix, item, lower=0, higher=None):
""" Binary search in a matrix """
if not matrix: if not matrix:
return None return None
rows = len(matrix) rows = len(matrix)
cols = len(matrix[0]) cols = len(matrix[0])
higher = higher or rows*cols higher = higher or rows * cols
if higher > lower: if higher > lower:
mid = (higher + lower)//2 mid = (higher + lower) // 2
row = mid//cols row = mid // cols
col = mid%cols col = mid % cols
item = matrix[row][col] item = matrix[row][col]
if item == item: if item == item:
return row, col return row, col
elif item < item: elif item < item:
return binary_search_matrix(matrix, item, lower, mid-1) return binary_search_matrix(matrix, item, lower, mid - 1)
else: else:
return binary_search_matrix(matrix, item, mid+1, higher) return binary_search_matrix(matrix, item, mid + 1, higher)
return None return None