Cody Boone Ferguson
9fdeaf1098
The manifest was updated for 1994/tvr. Rebuilt .entry.json and index.html. Bug status changed in 1994/tvr as well. The judges noted that it has an incorrect result in some cases but the author actually noted this as a feature so it should not be fixed. Other fixes/updates were made in the bugs file as well. A number of other entries of 1994 had minor fixes (formatting, links and similar things).
101 lines
3.3 KiB
Markdown
101 lines
3.3 KiB
Markdown
## To build:
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``` <!---sh-->
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make all
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```
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## To use:
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``` <!---sh-->
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./imc number
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```
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where `number` is an optional number. Default is 5.
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## Try:
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``` <!---sh-->
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./try.sh
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```
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## Judges' remarks:
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This entry's algorithm is as magic as its output!
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## Author's remarks:
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This program may be compiled with an ANSI or K&R compiler. A few
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harmless warnings are displayed only if `gcc -Wall` is used.
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This entry is really a set of library functions, but an example
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`main()` function has been added so that the library can be tested. If
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the program appears too large, consider that functions `o()` and `s()` can
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each be separated from the rest of the program (except for the short
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functions `p()` and `r()`, which they require) and used alone. However, the
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main part of the program is the function `e`, which does require all the
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other functions (apart from `main()`).
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The program should be supplied with an integer parameter. If no
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parameter or an invalid parameter is given, then 5 is assumed. The
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maximum parameter is determined only by the amount of CPU time, virtual
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memory and display (or file) space available.
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### NOTICE to those who wish for a greater challenge:
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**If you want a greater challenge, don't read any further**:
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just try to understand the program via the source.
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If you get stuck, come back and read below for additional hints and information.
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### How this entry works:
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OK, so you have probably seen magic square printers before. But what
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about one that deals with even sizes as well as odd ones, or one that
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prints out a different one each time (or attempts to, at any rate)?
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I have formatted the important functions `o()`, `s()` and `e()` to show how useful
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the word `for` is, and (in function `e()`) how useful the words `if` and
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`else` are. In fact, hardly anything happens that isn't in one of these
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instructions. I did this in order to simplify the code - the algorithms
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used to make the random squares are quite complex without being shrouded
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in obfuscated code! :-) Incidentally, I was surprised to find out how
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useful the exclusive-or operator was while writing function `s()`.
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Here are the descriptions of the functions in the library:
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> `o(n,a,q,d)`: makes a magic square of order `n` when `n` is odd and at least 3.<br>
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> `s(n,a,q,d)`: makes a magic square of order `n` when `n` equals 4.<br>
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> `e(n,a,q,d)`: makes a magic square of order `n` when `n` is even and at least 6.
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In the above, `a` (of type `int *`) points to an area of memory in which
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the magic square will be stored and `q` (also of type `int *`) points to
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an area of memory of length at least `n*sizeof(int)` bytes which can be
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used as a work space. Both `a` and `q` must be allocated by the caller.
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The integer parameter `d`, usually zero, indicates the length of a gap
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which will be left between adjacent rows of the magic square.
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The square which is returned will (or should) be a permutation of the
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numbers 1 to `n*n` in which all rows and columns and the two diagonals
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add up to `n*(n*n+1)/2`.
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<!--
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Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
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You are free to share and adapt this file under the terms of this license:
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Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
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For more information, see:
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https://creativecommons.org/licenses/by-sa/4.0/
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-->
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