binary search

binary_search.py

arr = [1,2,3,4,5,6,8,9,10,12,13,15]

def binary_search(a, v):
    s = 0
    e = len(a) - 1
    mid = (s+e)/2
    
    while s <= e:
        if a[mid] == v:
            return mid
        elif a[mid] < v:
            s = mid + 1
            mid = (s+e)/2
        elif a[mid] > v:
            e = mid - 1
            mid = (s+e)/2
    
    return -1

print binary_search(arr, 9)
print binary_search(arr, 0)
print binary_search(arr, 16)
print binary_search(arr, 15)
print binary_search(arr, 1)
print binary_search(arr, 5)