TooDumbToWin's blog

Comments affecting runtime?
By TooDumbToWin, history, 8 years ago, In English

I ran these codes in custom invocation and got weird running times.


#include<bits/stdc++.h>
using namespace std;
int main(){
    //Hi
    for(int i=0;i<5000000;i++)cout<<i<<" ";
    return 0;
}

Run time: 2448 ms


#include<bits/stdc++.h>
using namespace std;
int main(){
    for(int i=0;i<5000000;i++)cout<<i<<" ";
    return 0;
}

Run time: 2901 ms

Can anyone explain why adding comment is having significant impact on running times?

PS: Changing comment affected run time slightly as well.

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8 years ago, # |
  Vote: I like it +24 Vote: I do not like it

I guess it should just be difference between each runs. And codeforces caches your submission so if you submit one multiple times, it will return the same result.

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    "I guess it should just be difference between each runs." I didn't get you. Can you please rephrase the statement?

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      8 years ago, # ^ |
        Vote: I like it +5 Vote: I do not like it

      Due to dynamic CPU frequency, server load or some other reasons, time required for processing the same data by identical program may varies. As a result, several runs of a program may result different time consumed.

      Sorry for my bad English, hope this makes more sense.

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        8 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        As Laakeri has mentioned, the difference is quite high (450 ms).

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          8 years ago, # ^ |
          ← Rev. 2   Vote: I like it +5 Vote: I do not like it

          This extent of difference is possible, at least on my machine (the result of running OP's program):

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            8 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

            So I can get AC/TLE with same code depending upon server status? That's not really good. :/

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    8 years ago, # ^ |
      Vote: I like it +23 Vote: I do not like it

    Online judge should not be so unstable that time difference between runs of the same program is over 400 ms.

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8 years ago, # |
  Vote: I like it +16 Vote: I do not like it

Tried it 8 times. If I change the comment for "Petr" it works.

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    8 years ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

    CodeForces doesn't recompile your code if it's the same (at least in some time window)

    so tried 8 times may mean that result just was cached

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      8 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Took that into account. I tried it on different windows and making changes on the code.

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