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POHow to implement a dealer class without storing a deck of cards?
 

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  1. POHow to implement a dealer class without storing a deck of cards?
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    <ul> <li><p><strong>Question</strong></p> <p>Even only 52 cards, the <code>permutationIndex</code> where I describe in <em>Explanations</em> section, would be a huge number; it is a number in one of <code>52!</code>, and need 29 bytes to store. </p> <p>Thus <strong>I don't know a simple way</strong> to calculate the <code>permutationIndex</code> of a huge range, and store the index with a mininal cost, or maybe it can also be calculated. I'm thinking solution of this question would be three algorithms:</p> <ol> <li><p>An algorithm which compute the correct <code>permutationIndex</code> to <strong>implement the <code>Dealing</code></strong> method </p></li> <li><p>An algorithm which compute the correct <code>permutationIndex</code> to <strong>implement the <code>Collect</code></strong> method </p></li> <li><p>An algorithm which stores(or computes) <code>permutationIndex</code> <strong>with a minimal cost</strong></p></li> </ol></li> <li><p><strong>Explanations</strong></p> <p>I originally try to implement a <em>integer handle generator</em> of a range from <code>int.MinVale</code> to <code>int.MaxValue</code> using permutation. </p> <p>Because the range is really huge for that, thus I start from implement <strong><em>a <code>Dealer</code> class with 52 cards which doesn't really store a deck of cards</em></strong> like hashset or array, and even <strong>don't want random</strong>(except initial). </p> <p>With a given range of ordinal numbers, I consider every sequence of one of full permutations has a index, and named it <code>permutationIndex</code>. I use the index to remember which permutation it is and don't really store a sequence. The sequence is one of the possible order of the deck of card. </p> <p>And here is an example of emulation in animated graphics to show what I thought of. <img src="https://i.stack.imgur.com/wyZKK.gif" alt="Enter image description here"> </p> <p>Everytime I dealt a card, I change the <code>permutationIndex</code> and <code>dealt</code>(count of dealt cards), that I know which cards are those dealt, and which are still in hand. When I collect a dealt card back, I'll know the card number, and put it on the top, it's also become the card for next time to deal. In the animation, <code>colleted</code> is the <em>card number</em>. </p></li> </ul> <hr> <p>For more information, as follows. </p> <ul> <li><p>Description of code</p> <p>A conceptual sample <code>Dealer</code> class for only three 3 is as following. The code is written in <a href="/questions/tagged/c%23" class="post-tag" title="show questions tagged &#39;c#&#39;" rel="tag">c#</a>, and I'm also considering any <a href="/questions/tagged/language-agnostic" class="post-tag" title="show questions tagged &#39;language-agnostic&#39;" rel="tag">language-agnostic</a> solutions. </p> <p>Here're some descriptions of the sample code</p> <blockquote> <ul> <li><p>With the method <code>Dealing()</code>, we get a <em>number</em> of the card which treat as dealt. It always returns the <strong><em>right most</em></strong> number (relevant to the array) and then rolls the number left from it (say the next available) to the right most position by changing <code>permutationIndex</code>.</p></li> <li><p>The method <code>Collect(int)</code> is for collecting and put the dealt cards back into the deck. It would change <code>permutationIndex</code> also, according to what the <em>number</em> of card was returned back to the dealer.</p></li> <li><p>The integer <code>dealt</code> tells how many cards we've dealt; from the <strong><em>left most</em></strong> to the count stored in <code>dealt</code> are dealt cards. With <code>permutationIndex</code>, we know the sequence of cards.</p></li> <li><p>The <code>int[,]</code> array in the sample code is not used, just for helping imagine the permutations. The <em>switch</em> statements are considered to be implemented with algorithms which compute for the <code>permutationIndex</code>.</p></li> <li><p>The <code>permutationIndex</code> is the same thing described in this answer of <br/> <a href="https://stackoverflow.com/questions/1506078/fast-permutation-number-permutation-mapping-algorithms/1506337#1506337">Fast permutation -&gt; number -&gt; permutation mapping algorithms</a></p></li> </ul> </blockquote></li> <li><p>Sample code</p> <pre><code>public static class Dealer { public static void Collect(int number) { if(1&gt;dealt) throw new IndexOutOfRangeException(); switch(permutationIndex) { case 5: case 0: switch(number) { case 3: break; case 2: permutationIndex=1; break; case 1: permutationIndex=4; break; } break; case 4: case 3: switch(number) { case 3: permutationIndex=5; break; case 2: permutationIndex=2; break; case 1: break; } break; case 2: case 1: switch(number) { case 3: permutationIndex=0; break; case 2: break; case 1: permutationIndex=3; break; } break; } --dealt; } public static int Dealing() { if(dealt&gt;2) throw new IndexOutOfRangeException(); var number=0; switch(permutationIndex) { case 5: permutationIndex=3; number=3; break; case 4: permutationIndex=0; number=1; break; case 3: permutationIndex=1; number=1; break; case 2: permutationIndex=4; number=2; break; case 1: permutationIndex=5; number=2; break; case 0: permutationIndex=2; number=3; break; } ++dealt; return number; } static int[,] sample= new[,] { { 1, 2, 3 }, // 0 { 1, 3, 2 }, // 1 { 3, 1, 2 }, // 2 { 3, 2, 1 }, // 3 { 2, 3, 1 }, // 4 { 2, 1, 3 }, // 5 }; static int permutationIndex; static int dealt; } </code></pre></li> </ul>
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    1. COWhy not use auto-incremented value to get a new handle?
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    2. CO@KenKin, for example, you want the handle 1 will be available after `Release(1)`, i.e. next `GetHandle()` call will return handle 1?
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    3. COShouldn't this have a [tag:homework] tag? Edit: The tag is obsolete, however, should the question state it is a homework question?
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