binary_search.py

import sys

def search_func(initial, terminal, search_val, elements, position) :
	# print (initial," to ",terminal)
	difference = terminal - initial
	#print "Diff :" , position + difference
	elements = elements[initial:terminal]
	length = len(elements)

	if length > 1 :

		print "Searching at: ",elements
	
		mid = length/2
		#print("Mid position", mid)

		if mid > 0:
			
			element_mid = elements[mid]
			
			print "Middle element: ", element_mid
		
			if element_mid == search_val :
		
				print "Element found at the middle ", search_val ," at ",position
	
			elif element_mid > search_val :
				print ""
				print("Searching Left...")
				position = position - mid
				initial = 0
				search_func(initial, mid, search_val, elements, position)

			elif element_mid < search_val :
				print ""
				print("Searching Right...")
				position = position + mid
				search_func(mid + 1, length, search_val, elements, position)

		else :

			print "Not Found"

	elif length > 0 and elements[length - 1] == search_val :
		
		print "Element found: ", search_val, " at ", position

	else :
		print "Element not found...!", search_val

#####################################################################################

elements = [10,20,30,40,50,60,70,80,90,100,110,120,130,140,150,160,170,180,190,200]

"""elements = []

for x in xrange(0,5):
	prompt = "Enter the element at " + str(x) +": "
	val = input(prompt)
	elements.append(val)"""

length = len(elements)
position = 0

print "Your list" ,elements,"\n"

search_val = input("Enter the element to search:")
print ""

if length > 1:
	
	mid = length/2
	position = mid
	element_mid = elements[mid]
	print "Middle element: ", element_mid
	
	if element_mid == search_val :
		
		print "Element found at the middle: ", search_val, " at ", position

	elif element_mid > search_val :
		print ""
		print("Searching Left...")
		initial = 0
		search_func(initial, mid, search_val, elements, position)

	elif element_mid < search_val :
		print ""
		print("Searching Right...")
		search_func(mid + 1, length, search_val, elements, position)

	else :

			print "Not Found"

elif length > 0 and elements[length - 1] == search_val :

	print "Element found: ", search_val, " at ",position

else :
	print "Element not found...!", search_val