Author: Anthony Cozzie
Date: 14:04:06 02/22/05
Go up one level in this thread
On February 22, 2005 at 15:49:26, Steffen Jakob wrote:
>On February 22, 2005 at 15:43:44, Scott Gasch wrote:
>
>>On February 22, 2005 at 09:20:31, Steffen Jakob wrote:
>>
>>>On February 22, 2005 at 08:35:07, Andrew Wagner wrote:
>>>
>>>>Hi all.
>>>>I got sidetracked this morning by an interesting chess programming problem. It
>>>>took me a couple hours, but I think I have a working algorithm -- haven't tested
>>>>yet though. Anyway, I got to wondering if others would approach it the same way.
>>>>So I thought I'd make a little competition of it. Post your code here, and I'll
>>>>pick the program I like best and shower praise and adulation on its author. If
>>>>people like this challenge, maybe I'll do one each month or something. Anyway,
>>>>here's the one I did this morning:
>>>>There are 64 x 63 = 4032 ways to put a black knight and white knoght both on a
>>>>chess board. Write a program -- from scratch -- to generate FENs for each of
>>>>these positions. The FENs should look something like: Nn6/8/8/8/8/8/8/8 w - - 0
>>>>1.
>>>>
>>>>I think my code will wind up weighing in at around 60-70 lines of C. Can you do
>>>>better?
>>>
>>>Here is a quick hack. Without comments, with place to optimize, also almost
>>>untested, but shorter than yours ;-)
>>>
>>>
>>>#include <iostream>
>>>
>>>int GetFile(int square) { return square & 7; }
>>>int GetRank(int square) { return square >> 3; }
>>>
>>>int main(int argc, char** argv) {
>>> for(int white_knight = 0; white_knight < 64; ++white_knight) {
>>> for(int black_knight = 0; black_knight < 64; ++black_knight) {
>>> if(white_knight == black_knight) {
>>> continue;
>>> }
>>>
>>> for(int rank = 7; rank >= 0; --rank) {
>>> int n_empty = 0;
>>> for(int file = 0; file <= 7; ++file) {
>>> if(rank == GetRank(white_knight) && file == GetFile(white_knight)) {
>>> if(n_empty > 0) {
>>> std::cout << n_empty;
>>> }
>>> std::cout << "N";
>>> n_empty = 0;
>>> }
>>> else if(rank == GetRank(black_knight) && file == GetFile(black_knight)) {
>>> if(n_empty > 0) {
>>> std::cout << n_empty;
>>> }
>>> std::cout << "n";
>>> n_empty = 0;
>>> }
>>> else {
>>> ++n_empty;
>>> }
>>> }
>>> if(n_empty > 0) {
>>> std::cout << n_empty;
>>> }
>>> if(rank != 0) {
>>> std::cout << "/";
>>> }
>>> }
>>> std::cout << " w - - 0 1" << std::endl;
>>> }
>>> }
>>>
>>> return 0;
>>>}
>>
>>[ scott@wannabe:~/tmp ] % g++34 -O -S steffen.cpp ; wc -l steffen.s
>> 557 steffen.s
>
>Most of this code is because of using streams. If I replace them by printf,
>define the GetXXX() functions inline and compile the code with gcc instead of
>g++ I get 148 assembler lines.
>
>Best wishes,
>Steffen.
The lesson being that C++ streams blow, but we knew that anyway :)
anthony
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