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POSudoku checker algorithm in C++
 

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  1. POSudoku checker algorithm in C++
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    <p>I'm currently working on an algorithm to find all numbers with 9 digits using numbers 1-9 without any repeats. I'm testing a theory I have that filtering numbers as such will make for a more efficient sudoku checker.</p> <p>The code that I implemented does the following. It uses a for loop for places 1-9 in a number, such that (a)(b)(c)(d)(e)(f)(g)(h)(i) = #########. </p> <p>My theory is that by checking if the sum of the numbers (a-i) is equal to 45, that the product of a through i is equal to 9! and that the sum of the inverses of a-i is equal to roughly 2.828968 (or 1 + 1/2 + 1/3 ... 1/9)</p> <p>The issue is that after I filter the 9-digit numbers by the sum of the inverses of a-i, the count of possible 9-digit numbers predicted is less than 9! (the actual amount of possible numbers). I'm not sure why it's filtering so much, but the numbers that it does catch do not have any repeats (which is good). </p> <p>My thoughts are that the way I am playing with doubles is messing up the algorithm.</p> <p>Here is my code:</p> <pre><code>#include &lt;iostream&gt; #include &lt;iomanip&gt; using namespace std; int main() { int product; int sum; int count=0; double inverseSum; double correctInverseSum=(1.0/1.0)+(1.0/2.0)+(1.0/3.0)+(1.0/4.0)+(1.0/5.0)+ (1.0/6.0)+(1.0/7.0)+(1.0/8.0)+(1.0/9.0); for(double a=1.0; a&lt;10.0; a++){ for(double b=1.0; b&lt;10.0; b++){ for(double c=1.0; c&lt;10.0; c++){ for(double d=1.0; d&lt;10.0; d++){ for(double e=1.0; e&lt;10.0; e++){ for(double f=1.0; f&lt;10.0; f++){ for(double g=1.0; g&lt;10.0; g++){ for(double h=1.0; h&lt;10.0; h++){ for(double i=1.0; i&lt;10.0; i++){ product=a*b*c*d*e*f*g*h*i; sum=a+b+c+d+e+f+g+h+i; if(product==9*8*7*6*5*4*3*2*1 &amp;&amp; sum==45){ inverseSum=(1.0/a)+(1.0/b)+(1.0/c)+(1.0/d)+ (1.0/e)+(1.0/f)+(1.0/g)+(1.0/h)+(1.0/i); if(inverseSum==correctInverseSum) { count++; } } } } } } } } } } } cout&lt;&lt;"This is the count:"&lt;&lt;count&lt;&lt;endl; return 0; } </code></pre>
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    1. COI haven't seen so many nested for-loops in my entire life!
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    2. COWhat is your question? And @PaulManta is right, the code is scary :D
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    3. COHaha yeah I know it's awful, I am testing a theory I have. This code won't actually be implemented into my sudoku checker. My question is why is it giving me only 112112 results after filtering the 9-digit numbers instead of 9! (362880) theoretical possibilities of 9-digit numbers with no repeats.
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