def equalizer(unequal: list) -> list:
    """
    Equalize numbers between bigger or smaller numbers.

    [1, 4, 1]  # -> [1, 3, 1]
    [1, 2]  # -> [1, 2]
    [1, 4, 1, 0, 2]  # -> [1, 3, 1, 1, 2]

    :param unequal: Unequalized list.
    :return: Equalized list.
    """
    result = []

    for i in range(1, len(unequal) - 1):
        number = unequal[i]
        if unequal[i - 1] < number > unequal[i + 1]:
            a = -1
        elif unequal[i - 1] > number < unequal[i + 1]:
            a = 1
        else:
            a = 0
        result.append(number + a)
    return [unequal[0]] + result + [unequal[-1]]


if __name__ == '__main__':
    print(equalizer([1, 2, 3, 4]))  # [1, 2, 3, 4]
    print(equalizer([1, 2, 1, 2]))  # [1, 1, 1, 2]
    print(equalizer([1, 3, 1, 3]))  # [1, 2, 2, 3]