BARBARIANNNNN's blog

A strange thing
By BARBARIANNNNN, history, 2 years ago, In English

There is a strange thing between C++14 and C++20

We can see that the down two code are same, but the code using C++20 got TLE, and the code using C++14 got AC

https://codeforces.com/contest/1634/submission/145631828

https://codeforces.com/contest/1634/submission/145633066

We can also see that the down two code are same, but the code using C++14 got TLE, and the code using C++20 got AC

https://codeforces.com/problemset/submission/573/145373496

https://codeforces.com/problemset/submission/573/145372752

What's wrong with it? It there anyone could help me answer the question? Many Thanks!

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Comments Comments (17)
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2 years ago, # |
  Vote: I like it +8 Vote: I do not like it

in the second case, it is due to the 64-bit version of the compiler.

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2 years ago, # |
← Rev. 2   Vote: I like it +3 Vote: I do not like it

C++20(64-bit) is absolutely faster than C++20.

One of my friends named EasonTAO debugged the whole night and submitted for 94 times and got all TLE because he used C++20. Later he used C++20(64-bit) and submitted the same code and got AC.

It was really surprising.

Here is his submission.

143979222

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    2 years ago, # ^ |
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    That's really amazing that C++(64-bit) can run so fast.

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

      hahaha I used C++17(64-bit) and got AC while it's O(N^2) and N=1e5 :)

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        2 years ago, # ^ |
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        That's true. It seems that legacy problems can be passed with even the naive solution.:)

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

        hahaha I used C++17(64-bit) and got TLE while it's O(N^2) and N=1e4 :)

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    2 years ago, # ^ |
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    NO，I got TLE because I used C++14,Two hours later,I used C++17(64 bit) and submitted the same code and got AC.

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      2 years ago, # ^ |
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      I'm very suprised when I got AC.

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        2 years ago, # ^ |
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        I was very surprised at that time too.

        By the way, using O3 is also important when you are dealing with a qualmish problem.

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          2 years ago, # ^ |
            Vote: I like it +77 Vote: I do not like it

          Why not Ofast

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            2 years ago, # ^ |
              Vote: I like it -13 Vote: I do not like it

            There is Ofast too

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            2 years ago, # ^ |
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            I used O3,O2,Ofast and many other amazing things

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              2 years ago, # ^ |
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              You used the O3 I gave to you

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          2 years ago, # ^ |
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          At that time I was suprised that cin is faster than scanf!

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            2 years ago, # ^ |
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            yeah, and also faster than read(int &x) once I got TLE(501ms) while using read() :(

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

              Someone's "Fast Read":

              int fread(){
    int x;
    cin>>x;
    return x;
}

              ()()()

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2 years ago, # |
  Vote: I like it -19 Vote: I do not like it

EasonTAO, yyds!

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