# BinarySearch.py is a simple binary search program for python. It accepts an
# ordered list of ints and an int to look for in that list and returns the index
# of the number if found, if not found it returns -1
# Preconditions:vals must be of an array of sorted ints (in increasing order)
# and i must be an int.
# Postconditions: BinarySearch returns the index of the i or -1 if not found
import  string

#Binary Search    
def binary_search(i, vals):
#keep track of the end and beginning
   end = len(vals)
   beg = 0
#keep looking at smaller portions of the list until i is found
   while end > beg:
       mid = (beg+end)//2
       midvalue = vals[mid]
       if midvalue < i:
           beg = mid +1
       elif midvalue > i:
           end = mid
       elif midvalue == i:
           return mid

   return -1