""" Binary Search Algorithm
----------------------------------------
"""
#iterative implementation of binary search in Python
def binary_search(a_list, item):
"""Performs iterative binary search to find the position of an integer in a given, sorted, list.
a_list -- sorted list of integers
item -- integer you are searching for the position of
"""
first = 0
last = len(a_list) - 1
while first <= last:
i = (first + last) / 2
if a_list[i] == item:
return ' found at position '.format(item=item, i=i)
elif a_list[i] > item:
last = i - 1
elif a_list[i] < item:
first = i + 1
else:
return ' not found in the list'.format(item=item)
#recursive implementation of binary search in Python
def binary_search_recursive(a_list, item):
"""Performs recursive binary search of an integer in a given, sorted, list.
a_list -- sorted list of integers
item -- integer you are searching for the position of
"""
first = 0
last = len(a_list) - 1
if len(a_list) == 0:
return ' was not found in the list'.format(item=item)
else:
i = (first + last) // 2
if item == a_list[i]:
return ' found'.format(item=item)
else:
if a_list[i] < item:
return binary_search_recursive(a_list[i+1:], item)
else:
return binary_search_recursive(a_list[:i], item)