about summary refs log blame commit diff stats
path: root/html/nqueens.mu.html
blob: 1053e8da3627b1d4fd143928ef22ca4fe093a651 (plain) (tree)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15














                                                                                                 
                           
                              



                              
                             












                                                                                                                                                  

                                                          

                                              

          

 
                                                                                                                                                    


                                                                                        
                                                                   
                                  
                                                                                  

                                                     
                                                                         

                                                 
                                                                                       

                                                      


                                                                                                             
                                  

                                                                                       
                                  
                                                                               
                                                 
                                                                             
                                    
                                                                                    
                                                             

                                                                                   
                                                                      
                                                           
                                    
                                                                                               



                                       
                                                                                                                                   

                                                
                                                                                
                                                           
                                                                                    
                                               

 
                                                                                                                                           

                                                
                                                                                                      

                                                      


                                                                                                 
                                                                                                        
                                                         

                                       
                                                                                         

 
                                                                                                                                               

                                                

                                                                                                      

                                                      







                                                                                                 
                                                                                                            
                                                         

                                       
                                                                                         
 

                                        
                                         

                                                 



                                     
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Mu - nqueens.mu</title>
<meta name="Generator" content="Vim/7.4">
<meta name="plugin-version" content="vim7.4_v2">
<meta name="syntax" content="none">
<meta name="settings" content="use_css,pre_wrap,no_foldcolumn,expand_tabs,prevent_copy=">
<meta name="colorscheme" content="minimal">
<style type="text/css">
<!--
pre { white-space: pre-wrap; font-family: monospace; color: #eeeeee; background-color: #080808; }
body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color: #080808; }
* { font-size: 12pt; font-size: 1em; }
.muData { color: #ffff00; }
.muControl { color: #c0a020; }
.Delimiter { color: #800080; }
.Comment { color: #9090ff; }
.Constant { color: #00a0a0; }
.Special { color: #c00000; }
.muRecipe { color: #ff8700; }
-->
</style>

<script type='text/javascript'>
<!--

-->
</script>
</head>
<body>
<pre id='vimCodeElement'>
<span class="Comment"># <a href="http://rosettacode.org/wiki/N-queens_problem">http://rosettacode.org/wiki/N-queens_problem</a></span>
<span class="Comment"># port of the Arc solution at <a href="http://arclanguage.org/item?id=19743">http://arclanguage.org/item?id=19743</a></span>
<span class="Comment"># run with tracing turned on:</span>
<span class="Comment">#   ./mu --trace nqueens.mu</span>

<span class="muData">container</span> square [
  rank:num
  file:num
]

<span class="muRecipe">def</span> nqueens n:num, queens:&amp;:list:square<span class="muRecipe"> -&gt; </span>result:num, queens:&amp;:list:square [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="Comment"># if 'queens' is already long enough, print it and return</span>
  added-so-far:num <span class="Special">&lt;-</span> length queens
  <span class="Delimiter">{</span>
    done?:bool <span class="Special">&lt;-</span> greater-or-equal added-so-far, n
    <span class="muControl">break-unless</span> done?
    stash queens
    <span class="muControl">return</span><span class="Constant"> 1</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># still work to do</span>
  next-rank:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> queens
    first:square <span class="Special">&lt;-</span> first queens
    existing-rank:num <span class="Special">&lt;-</span> get first, <span class="Constant">rank:offset</span>
    next-rank <span class="Special">&lt;-</span> add existing-rank,<span class="Constant"> 1</span>
  <span class="Delimiter">}</span>
  result <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
  next-file:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
  <span class="Delimiter">{</span>
    done?:bool <span class="Special">&lt;-</span> greater-or-equal next-file, n
    <span class="muControl">break-if</span> done?
    curr:square <span class="Special">&lt;-</span> merge next-rank, next-file
    <span class="Delimiter">{</span>
      curr-conflicts?:bool <span class="Special">&lt;-</span> conflict? curr, queens
      <span class="muControl">break-if</span> curr-conflicts?
      queens:&amp;:list:square <span class="Special">&lt;-</span> push curr, queens
      sub-result:num <span class="Special">&lt;-</span> nqueens n, queens
      result <span class="Special">&lt;-</span> add result, sub-result
      queens <span class="Special">&lt;-</span> rest queens
    <span class="Delimiter">}</span>
    next-file <span class="Special">&lt;-</span> add next-file,<span class="Constant"> 1</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
]

<span class="muRecipe">def</span> conflict? curr:square, queens:&amp;:list:square<span class="muRecipe"> -&gt; </span>result:bool [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  result1:bool <span class="Special">&lt;-</span> conflicting-file? curr, queens
  <span class="muControl">return-if</span> result1, result1
  result2:bool <span class="Special">&lt;-</span> conflicting-diagonal? curr, queens
  <span class="muControl">return</span> result2
]

<span class="muRecipe">def</span> conflicting-file? curr:square, queens:&amp;:list:square<span class="muRecipe"> -&gt; </span>result:bool [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  curr-file:num <span class="Special">&lt;-</span> get curr, <span class="Constant">file:offset</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> queens
    q:square <span class="Special">&lt;-</span> first queens
    qfile:num <span class="Special">&lt;-</span> get q, <span class="Constant">file:offset</span>
    file-match?:bool <span class="Special">&lt;-</span> equal curr-file, qfile
    <span class="muControl">return-if</span> file-match?, <span class="Constant">1/conflict-found</span>
    queens <span class="Special">&lt;-</span> rest queens
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
  <span class="muControl">return</span> <span class="Constant">0/no-conflict-found</span>
]

<span class="muRecipe">def</span> conflicting-diagonal? curr:square, queens:&amp;:list:square<span class="muRecipe"> -&gt; </span>result:bool [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  curr-rank:num <span class="Special">&lt;-</span> get curr, <span class="Constant">rank:offset</span>
  curr-file:num <span class="Special">&lt;-</span> get curr, <span class="Constant">file:offset</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> queens
    q:square <span class="Special">&lt;-</span> first queens
    qrank:num <span class="Special">&lt;-</span> get q, <span class="Constant">rank:offset</span>
    qfile:num <span class="Special">&lt;-</span> get q, <span class="Constant">file:offset</span>
    rank-delta:num <span class="Special">&lt;-</span> subtract qrank, curr-rank
    file-delta:num <span class="Special">&lt;-</span> subtract qfile, curr-file
    rank-delta <span class="Special">&lt;-</span> abs rank-delta
    file-delta <span class="Special">&lt;-</span> abs file-delta
    diagonal-match?:bool <span class="Special">&lt;-</span> equal rank-delta, file-delta
    <span class="muControl">return-if</span> diagonal-match?, <span class="Constant">1/conflict-found</span>
    queens <span class="Special">&lt;-</span> rest queens
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
  <span class="muControl">return</span> <span class="Constant">0/no-conflict-found</span>
]

<span class="muRecipe">def</span> main [
  nqueens<span class="Constant"> 4</span>
  $dump-trace <span class="Constant">[app]</span>
]
</pre>
</body>
</html>
<!-- vim: set foldmethod=manual : -->