What does “O(1) access time” mean?

Question

I have seen this term \"O(1) access time\" used to mean \"quickly\" but I don\'t understand what it means. The other term that I see with it in the same context is \"O(n) ac

Answer 1

Here is a simple analogy; Imagine you are downloading movies online, with O(1), if it takes 5 minutes to download one movie, it will still take the same time to download 20 movies. So it doesn't matter how many movies you are downloading, they will take the same time(5 minutes) whether it's one or 20 movies. A normal example of this analogy is when you go to a movie library, whether you are taking one movie or 5, you will simply just pick them at once. Hence spending the same time.

However, with O(n), if it takes 5 minutes to download one movie, it will take about 50 minutes to download 10 movies. So time is not constant or is somehow proportional to the number of movies you are downloading.