Same solution submitted twice and execution time differs by 0.6 points why?

Please give explanation.

This can happen due to various reasons:

  1. There might be a case where your program was ran with different set of inputs each time.
  2. Load on the server. In the second case, due to some cache unavailability or something related to memory, it might have took more time.

There have been cases where same solution got TLE and AC on different attempts. Ref #1 TLE, Ref #2 AC.

By the way, I did not find any such case in your submissions. So please give a link to where you saw this. And secondly, execution time is not measured in “points”, you could have written units if not seconds.

As @bugkiller mentioned, if you’re referring to a challenge problem, then the running time might be “dynamic” in the sense that different input sets might be used to check the correctness of your solution, and thus, some solutions might be AC on some given set and give TLE on another set.

If you’re referring to a binary problem however, then I believe that, as the input set is static, the only two reasons which might cause a difference in runtime I can think about are:

  • Changing to a different version of the same language:

Due to compiler optimizations and the judge configurations a code ran with gcc 4.3.2 and the same code ran with gcc 4.8.1 might yield some considerable differences in runtime. My experiences show differences in the order of 0.1 to 0.2 seconds using inline functions, which sometimes might be the difference between AC and TLE;

  • Server overloads

As stated on the submissions page, sometimes, if the server is “too crowded” that might also affect runtime;

All the best,

Bruno

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