sub_length.py

def sub_length(arr):
    """
    Given an array of n integers, find the length of the longest increasing subsequence

    :param arr: The array to parse
    :return: the length of the longest increasing subsequence
    """
    if not arr:
        return 0
    longest_streak = 1
    current_streak = 1
    highest = arr[0]
    for item in arr[1:]:
        if item >= highest:
            current_streak += 1
        else:
            if current_streak > longest_streak:
                longest_streak = current_streak
            current_streak = 1
        highest = item

    if current_streak > longest_streak:
        longest_streak = current_streak
    return longest_streak

def main():
    assert sub_length([1, 2, 3, 4]) == 4
    assert sub_length([1, 2, 3, 4, 4]) == 5
    assert sub_length([4, 3, 2, 1]) == 1
    assert sub_length([1, 2, 3, 2]) == 3
    assert sub_length([1, 5, 9, 54, 0]) == 4
    assert sub_length([13, 35, 1, 5, 40, 86]) == 4
    assert sub_length([13, 1, 5, 40, 86]) == 4
    assert sub_length([-13, -35, -86, -40, -5, -1]) == 4
    assert sub_length([]) == 0


if __name__ == '__main__':
    main()