binary_search

binary_search.py

def BS(arr, n):

    l, u = 0, len(arr)-1

    while l <= u:

        m = (l+u)//2

        if n == arr[m]:
            return m
        elif n < arr[m]:
            u = m-1
        else:
            l = m+1
    return -1

print(BS([1,2,3,4,5,6,7,8,9], 7))

print(BS([1,2,3,4,5,6,7,8,9], 10))

def BS(list, n):

    a = 0
    b = len(arr)-1
    while a <= b:

        c = (a+b)//2

        if n < arr[c]:
            b = c - 1
        elif n> arr[c]:
            a = c + 1
        else:
            return c
    return -1

print(BS([1,2,3,4,5,6,7,8,9], 7))

print(BS([1,2,3,4,5,6,7,8,9], 10))