python_binary_search_library.py

from bisect import bisect_left, bisect_right

# Locate the leftmost value exactly equal to x
def index_of_x(a, x):
 i = bisect_left(a, x)
 if i != len(a) and a[i] == x:
 return i
 return None

# Locate the rightmost value less than x
def index_of_less_than_x(a, x):
 i = bisect_left(a, x)
 if i:
 return i - 1
 return None

# Locate the rightmost value less than or equal to x
def index_of_less_or_equal_than_x(a, x):
 i = bisect_right(a, x)
 if i:
 return i - 1
 return None

# Locate the leftmost value greater than x
def index_of_greater_than_x(a, x):
 i = bisect_right(a, x)
 if i != len(a):
 return i
 return None

# Locate the leftmost value greater than or equal to x
def index_of_greater_equal_than_x(a, x):
 i = bisect_left(a, x)
 if i != len(a):
 return i
 return None

n = 10
target = 13
array = [1, 3, 5, 7, 9, 11, 13, 15, 17, 19]

result = index_of_x(array, target)
if result == None:
 print(None)
else:
 print(result + 1)