Binary Search

Search an exact number in array

def binary_search(arr, number_researched):
    # (l)eft and (r)ight pointer
    l, r = 0, len(arr) - 1
    while l <= r:
        m = (l + r) // 2 # (m)id which is equivalent to math.floor((l+r) / 2)
        if arr[m] < number_researched:
            l = m + 1
        elif arr[m] > number_researched:
            r = m - 1
        else:
            return r
    return r

Search closest number (floor)

def binary_search(arr, number_researched):
    # (l)eft and (r)ight pointer
    l, r = 0, len(arr) - 1
    while l < r:
        m = (l + r) // 2
        if arr[m] < number_researched:
            l = m + 1
        else: # elif arr[m] >= number_researched:
            r = m
    return r