Mong_Mang's blog

How to compile fast for Facebook Hacker Cup?
By Mong_Mang, history, 8 months ago, In English

In Facebook Hacker Cup 2022 Round 2, I coded a right O(n) solution (C++) for Problem A, but I downloaded the input test case and ran the code. but it took me around 8 minutes to get the output. As a result, I couldn't submit the output. However, after the contest, I submitted the output and got accepted. Can anyone please tell me how can I compile fast or overcome this problem or any suggestions regarding this?

Note: I use Codeblocks IDE. Sometimes I use VS Code.

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8 months ago, # |
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which IDE do you use

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    8 months ago, # ^ |
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    Codeblocks

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      8 months ago, # ^ |
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      In one of the Codeblocks toolbars, you can select Debug or Release. If you select Release, the solution will be compiled with -O2, which makes it much faster.

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8 months ago, # |
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What was the complexity of your solution? Are you sure it was meant to pass?

Also, compile with the -O2 flag.

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    8 months ago, # ^ |
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    The complexity of my solution is O(n).

    Can you please give me some details about -O2 flag.

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      8 months ago, # ^ |
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      Instead of compiling like g++ solution.cpp -o solution, compile as g++ solution.cpp -O2 -o solution.

      It enables certain optimizations, basically the compiler will be smarter and convert your code into a faster program.

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        8 months ago, # ^ |
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        Thank you. I'll try this and let you know.

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8 months ago, # |
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You might want to check how fast you're reading the input. If a correct C++ solution took around 8 minutes, IO would be the culprit. If that's the case, you should use Fast IO.

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8 months ago, # |
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how can I compile fast

If it's really a compilation what took so long (I doubt so) then just compile before downloading the input

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8 months ago, # |
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my laptop cannot handle running large input and output. Is there any online judge which can compile very fast.

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