RAD's blog

Codeforces Beta Round #49 (Div. 2)
By RAD, 15 years ago, translation, In English

Hi everyone!

The recent testing round went well. It is expected that everything will run faster. Today's round was prepared by: Mike Mirzayanov, Nickolay Kuznetsov, Ivan Fefer and Maria Belova.

Good luck!

Artem Rakhov and Codeforces team

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Comments Comments (33)
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15 years ago, hide # |
 
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2nd one is a little bit confusing.. Especially "If those rules don't indicate the size of the cut are clearly, then the way with which the cut part possesses the largest area is chosen."
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15 years ago, hide # |
 
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Was the site running extremely slowly or was it just my connection as both have been having their ups and down recently :P
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15 years ago, hide # |
 
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I have a little question about a challenge case in problem A of today's contest. In my room one coder wrote a subroutine where he checked for every address whether it matches with the "input" string. In order to do that, he run a for loop which checked character by character whether the "input" string matches with any of the addresses. His for loop runs like this:

for ( int i = 0 ; i < input.size() ; i ++ ) {
if(input[i]!=current_address[i]) break;
}

Now my question, shouldn't there be a runtime error when the size of the input is bigger than the current_address, given all the other characters are equal?

I challenged it and it failed. Can anyone explain why?
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  • 15 years ago, hide # ^ |
    ← Rev. 2  
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    what data type of input && current_address?
    As I know a[big_int] will return 0 if it is string

    upd:
    I tried this code in g++:
    string a("abcde");
    cout<<(int)a[17];

    It prints 0
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    • 15 years ago, hide # ^ |
       
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      Wouldn't there be an exception?
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      • 15 years ago, hide # ^ |
         
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        No any exceptions,errors.
        Just 0
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        • 15 years ago, hide # ^ |
           
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          You are wrong, as far as my tests tell.
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          • 15 years ago, hide # ^ |
             
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            Can you show me code you are tried?
            And.. language?
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            • 15 years ago, hide # ^ |
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              No problem. I used C++ and string. (as I suppose this is what is used in the solution shown above, though I am not sure).

              So I tried the following:

              int main()
              {
                  string str = "codeforces";
                  cout << str[11] << endl;
                  return 0;
              }

              It banged, crashed, exploded. Still, I agree that if current_address is char[], then the code will not crash and everything will go smoothly, exactly because of the '\0' character you spoke of.
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              • 15 years ago, hide # ^ |
                 
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                do you use MS Visual C++?
                I tried this code:
                #include <string>
                #include <iostream>
                using namespace std;
                int main()
                {
                    string str = "codeforces";
                    cout << str[12] << endl;
                    return 0;
                }
                it runs successful on my computer(g++) and in tab "Run" on codeforces (g++) but crashed in MS C++
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              • 15 years ago, hide # ^ |
                 
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                But '\0' is at str[10], not at str[11]. isnt it?
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                • 15 years ago, hide # ^ |
                   
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                  You are correct, now as I changed the index it really runs smoothly. Cool I did not know that.
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  • 15 years ago, hide # ^ |
     
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    Can you point to this solution?
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  • 15 years ago, hide # ^ |
     
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    Hm, if it is char[],first symbol after End of String will 0 too
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15 years ago, hide # |
 
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so, those who are not in div2, were not allowed to open any solution? or it was a problem here? I just wanted to see some people's code (no intention was for hacking :P) but it didn't allow me to do so...
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15 years ago, hide # |
 
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+83   and blue  :D , All effect of "rng"  thanx rng_58.
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15 years ago, hide # |
 
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Do we get tutorial for this contest?
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15 years ago, hide # |
 
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In problem B test 7,  the input is 99 100 and the answer is 80 64. But what if the answer is 64 80? My program told me the latter answer and I think it's more reasonable--people would usually like to cut pictures as consistent with the origin ratio as possible, wouldn't they?

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