BinarySearchIndex.py

import math 
def index(list1, n):
    startIndex = 0
    endIndex = len(list1) - 1
    
    while startIndex <= endIndex:
        mid = startIndex + int(math.floor((endIndex-startIndex)/2))
        if list1[mid] == n:
            print n
            print mid
            break
        elif n > list1[mid]:
            startIndex = mid + 1
        else:
            endIndex = mid
        
index([1,3,4,5,6,8,9,10,11,12],10)
             

mid = (endIndex+startIndex)/2