Discussion @ 1230. Introspective Program @ Timus Online Judge

An algorythm?(+) Илья Гофман (Ilya Gofman) 14 Nov 2002 13:40

Please, could you shortly tell me an algo of a introspective
program? In any language:-)

Me also. An algorithm for any language? asif 14 Nov 2002 14:51

Example of an introspective program on Pascal (+) Oberon (Yura Znovyak) 16 Nov 2002 13:38

Here is my variant of an introspective program. It is written on
Pascal. I think it will not be hard to convert it to C/C++
But I do not think it is easy make same under PIBAS, because
PIBAS does not have for/while cycles :(.

Some explanations:
1. Every const string (Stgs[ 2] := '...') Has " symbol not '
because Pascal needs doubled '' to mark single ' inside strings.
2. Chr(34) = '
3. Chr(39) = "

----- Cut here -----
program IntrospectiveProgram;
var
    Stgs: array[1..20] of String;
    i, j: Integer;

begin
    Stgs[ 1] := '';
    Stgs[ 2] := '    WriteLn("program IntrospectiveProgram;");';
    Stgs[ 3] := '    WriteLn("var");';
    Stgs[ 4] := '    WriteLn("    Stgs: array[1..20] of String;");';
    Stgs[ 5] := '    WriteLn("    i, j: Integer;");';
    Stgs[ 6] := '    WriteLn;';
    Stgs[ 7] := '    WriteLn("begin");';
    Stgs[ 8] := '';
    Stgs[ 9] := '    for i := 1 to 20 do';
    Stgs[10] := '         WriteLn("    Stgs[",i:2,"] := """, Stgs
[i], """;");';
    Stgs[11] := '    WriteLn;';
    Stgs[12] := '';
    Stgs[13] := '    for i := 1 to 20 do';
    Stgs[14] := '        for j := 1 to Length(Stgs[i]) do';
    Stgs[15] := '            if Stgs[i][j] = Chr(34) then';
    Stgs[16] := '                Stgs[i][j] := Chr(39);';
    Stgs[17] := '';
    Stgs[18] := '    for i := 1 to 20 do';
    Stgs[19] := '        WriteLn(Stgs[i]);';
    Stgs[20] := 'end.';

    WriteLn('program IntrospectiveProgram;');
    WriteLn('var');
    WriteLn('    Stgs: array[1..20] of String;');
    WriteLn('    i, j: Integer;');
    WriteLn;
    WriteLn('begin');

    for i := 1 to 20 do
         WriteLn('    Stgs[',i:2,'] := ''', Stgs[i], ''';');
    WriteLn;

    for i := 1 to 20 do
        for j := 1 to Length(Stgs[i]) do
            if Stgs[i][j] = Chr(34) then
                Stgs[i][j] := Chr(39);

    for i := 1 to 20 do
        WriteLn(Stgs[i]);
end.
---- And here ----

Thank you very much. Илья Гофман (Ilya Gofman) 16 Nov 2002 19:45

> Here is my variant of an introspective program. It is written on
> Pascal. I think it will not be hard to convert it to C/C++
> But I do not think it is easy make same under PIBAS, because
> PIBAS does not have for/while cycles :(.
>
> Some explanations:
> 1. Every const string (Stgs[ 2] := '...') Has " symbol not '
> because Pascal needs doubled '' to mark single ' inside strings.
> 2. Chr(34) = '
> 3. Chr(39) = "
>
> ----- Cut here -----
> program IntrospectiveProgram;
> var
>     Stgs: array[1..20] of String;
>     i, j: Integer;
>
> begin
>     Stgs[ 1] := '';
>     Stgs[ 2] := '    WriteLn("program IntrospectiveProgram;");';
>     Stgs[ 3] := '    WriteLn("var");';
>     Stgs[ 4] := '    WriteLn("    Stgs: array[1..20] of
String;");';
>     Stgs[ 5] := '    WriteLn("    i, j: Integer;");';
>     Stgs[ 6] := '    WriteLn;';
>     Stgs[ 7] := '    WriteLn("begin");';
>     Stgs[ 8] := '';
>     Stgs[ 9] := '    for i := 1 to 20 do';
>     Stgs[10] := '         WriteLn("    Stgs[",i:2,"] := """, Stgs
> [i], """;");';
>     Stgs[11] := '    WriteLn;';
>     Stgs[12] := '';
>     Stgs[13] := '    for i := 1 to 20 do';
>     Stgs[14] := '        for j := 1 to Length(Stgs[i]) do';
>     Stgs[15] := '            if Stgs[i][j] = Chr(34) then';
>     Stgs[16] := '                Stgs[i][j] := Chr(39);';
>     Stgs[17] := '';
>     Stgs[18] := '    for i := 1 to 20 do';
>     Stgs[19] := '        WriteLn(Stgs[i]);';
>     Stgs[20] := 'end.';
>
>
>     WriteLn('program IntrospectiveProgram;');
>     WriteLn('var');
>     WriteLn('    Stgs: array[1..20] of String;');
>     WriteLn('    i, j: Integer;');
>     WriteLn;
>     WriteLn('begin');
>
>     for i := 1 to 20 do
>          WriteLn('    Stgs[',i:2,'] := ''', Stgs[i], ''';');
>     WriteLn;
>
>     for i := 1 to 20 do
>         for j := 1 to Length(Stgs[i]) do
>             if Stgs[i][j] = Chr(34) then
>                 Stgs[i][j] := Chr(39);
>
>     for i := 1 to 20 do
>         WriteLn(Stgs[i]);
> end.
> ---- And here ----

Here's a C Quine :-) Gheorghe Stefan 9 Dec 2002 00:13

char *f = "char *f = %c%s%c; void main(){printf(f, 34, f, 34, 10);%c"
void main()
{
printf(f, 34, f, 34, 10);
}

Another idea marqueewinq 5 Nov 2011 03:43

The main point of my solution is, firstly, to become free of constant non-variable strings in output and, secondly, to use substring operator to replicate print.

Let's define double quote as D, and single quote as S, sembol of endline as E:
{{{
D='"';S="'";E=";"
}}}

After defining that, we need to print that string. Let's use support string C:
{{{
C="C=D=S=E=";
...
?$(C,1,2)+D+C+D+E #printed definition of C
+$(C,3,2)+S+D+S+E #printed definition of D
... #print the rest alike
}}}

But how we'll print this particular "?" operation? Let's append all that operator body to our support string C, and then print it's substring, which will represent needed operator:
{{{
C="C=D=S=E=?$(C,1,2)+D+C+D+E+$(C,3,2)+S+D+S+E+$(C,5,2)+D+S+D+E+$(C,7,2)+D+E+D+E+$(C,9,78)";
}}}

You can simply prove by yourself, that this substring is 78 symbols long.

Thus, solution found. My full PIBAS code is 187 lines long.

Edited by author 05.11.2011 03:44

Edited by author 05.11.2011 03:44

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