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POSudoku solver Recurrence stack with try and fail technique
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  1. POSudoku solver Recurrence stack with try and fail technique
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    copied!<p>I am building a Sudoku solver that use the Try and Fail technique to solve any problem. My algorithm is:</p> <p>1)Update (method that remove any possible value that already given as a final value to element in the same Row, column or squar)</p> <p>2)Get the minimum element that has minimum number of possible values</p> <p>3)start solve assuming the first possible value is the final value</p> <p>4)save the current sate into a stack</p> <p>5)Try to solve</p> <p>5-a)If solved, return </p> <p>5-b)if not solved and with invalid Sudoku, then Pop previous state </p> <p>6)Repeat step 3) for all possible vaues (9)</p> <p>7)Repeat step 2) until the puzzel is solved</p> <p>This is my code </p> <pre><code>Stack&lt;Element[][]&gt; myStack= new Stack&lt;&gt;(); private Element[][] mySudoku; public void solve(){ update();//remove all final values from all possible values for each element if(isSudokuSolved(mySudoku)){ return; } //find a cell that is not confirmed and has the minimal candidates int celli=-1,cellj=-1, p=10; for(int i=0;i&lt;9;i++){ for(int j=0;j&lt;9;j++){ if(mySudoku[i][j].getValue()==0){ if(mySudoku[i][j].getPossibleValues().size()&lt;p){ celli=i; cellj=j; p=mySudoku[i][j].getPossibleValues().size(); } } } } try { for (int c = 0; c &lt; mySudoku[celli][cellj].getPossibleValues().size() - 1; c++) { //save state Element[][] copy=deepCopy(mySudoku);//copy the current state myStack.push(copy); //apply candidate to cell mySudoku[celli][cellj].setValue(mySudoku[celli][cellj].getPossibleValues().get(c)); update();//check is solved if(checkValidInputSudoku(mySudoku)){ solve(); }else{ try { mySudoku = myStack.pop(); } catch (EmptyStackException est) { //do nothing } } } } catch (Exception e) { } //if we have reached here then we are at the last possible value for the candidates so confirm candidate in cell if(celli!=-1 &amp;&amp; cellj!=-1 &amp;&amp; p!=10) {//Some problems happen here "out of Boundry -1 Error" mySudoku[celli][cellj].setValue(mySudoku[celli][cellj].getPossibleValues().get(mySudoku[celli][cellj].getPossibleValues().size()-1)); } }//end of solve method </code></pre> <p>I have spent more than 6 hours trying to find out the problem. I have checked for the Update() method, deepCopy() method and checkValidInputSudoku() method. They all works fine. Thank you in Advance</p>
 

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