what's simplest way to find out complexity of any programme? Without using paper and pen..

Answer 1

It’s very simple really, when you write your own code, you know how many times you loop through the input, this is your time complexity.
While processing your input, you might want to make some containers along the way, this container size is your space complexity.
Keep in mind that big O complexity is measured on worst-case input.

Answer 2

Thanks