Same for me. I Solved 5 problems and yet got -2 rating

As rule of thumb, a common processor theses days, has at least 1GHz. So, it'll perform 10 ^ 9 operations in each cycle. So, in O (n) with n = 10 ^ 9, will be 10 ^ 9/10 ^ 9 = 1 second. Just remember that it's a rule of thumb. It's an asymptotic analysis. You won't get the real needed running time. If you run an algorithm in javascript and the same algorithm in C ++, you'll get different running times, even tough it's the same complexity. As it seems, doesn't make sense these type of comparisons. But, you know that if with O (n) takes 1 second at most, with O (n²) it will'be 10 ^ 18/10 ^ 9 = 10 ^ 9 seconds or 31 Years. It doesn't matter if it's 31 years and 2 days or 30 years and 300 days. It's still so much time, and is not a feasible solution.

See the table on top of this article

Hope that it'll help you

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