Binary search algotithm.py

# Function to determine if a `target` exists in the sorted list `nums`
# or not using a binary search algorithm
def binarySearch(nums, target):
    # search space is nums[left…right]
    (left, right) = (0, len(nums) - 1)

    # loop till the search space is exhausted
    while left <= right:

        # find the mid-value in the search space and
        # compares it with the target

        mid = (left + right) // 2

        # overflow can happen. Use:
        # mid = left + (right - left) / 2
        # mid = right - (right - left) // 2

        # target is found
        if target == nums[mid]:
            return mid

        # discard all elements in the right search space,
        # including the middle element
        elif target < nums[mid]:
            right = mid - 1

        # discard all elements in the left search space,
        # including the middle element
        else:
            left = mid + 1

    # `target` doesn't exist in the list
    return -1


if __name__ == '__main__':

    nums = [2, 5, 6, 8, 9, 10]
    target = 5

    index = binarySearch(nums, target)

    if index != -1:
        print('Element found at index', index)
    else:
        print('Element found not in the list')