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POEight Queens C++ utilizing a Stack Backtracking
 

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  1. POEight Queens C++ utilizing a Stack Backtracking
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    <p>So I'm doing this for homework, and I can't figure out where my bug is. Any help is greatly appreciate.</p> <p>My understanding is this.</p> <ol> <li>Initialize a stack for tracking which row &amp; column has a queen in it.</li> <li>Place a queen on the first square, push its location onto the stack. Push (0,0); Then set a variable that the row has been filled. filled+;</li> </ol> <p>3.Then Loop</p> <p>check if the current row or column have a conflict with another queen.</p> <p>a. no conflict. push to stack. increase the filled row variable. filled++; move up a row.</p> <p>b. there is a conflict. Move right. col++;</p> <p>c. cant move right anymore. pop the stack and set to row and col. subtract the filled. then move over. col++; and try again.</p> <hr> <pre><code>int main(){ bool board[8][8]; for(int i = 0; i &lt; 8; i++){ for(int j = 0; j &lt; 8; j++){ board[i][j] = false;}} int row = 0, col = 0, filled = 0; StackLi&lt;int&gt; rowStack; StackLi&lt;int&gt; colStack; rowStack.push(row); colStack.push(col); board[row][col] = true; //cout &lt;&lt; "push: " &lt;&lt; "(" &lt;&lt; row &lt;&lt; "," &lt;&lt; col &lt;&lt; ")" &lt;&lt; endl; row++; while(filled &lt; 7) { if(!isSafe(board,row,col) ) { filled++; rowStack.push(row); colStack.push(col); board[row][col] = true; //cout &lt;&lt; "push: " &lt;&lt; "(" &lt;&lt; row &lt;&lt; "," &lt;&lt; col &lt;&lt; ")" &lt;&lt; endl; if(filled &gt; 8) { print(board); return 0; } row++; } else{ col++; //cout &lt;&lt; "move: " &lt;&lt; "(" &lt;&lt; row &lt;&lt; "," &lt;&lt; col &lt;&lt; ")" &lt;&lt; endl; } if(col &gt; 7) { row = rowStack.topAndPop(); col = colStack.topAndPop(); board[row][col] = false; cout &lt;&lt; "pop: " &lt;&lt; "(" &lt;&lt; row &lt;&lt; "," &lt;&lt; col &lt;&lt; ")" &lt;&lt; endl; filled--; } } return 0; } bool isSafe(bool board[8][8], int row, int col) { for(int i = 0; i &lt; 8; i++) { if(board[row][i] || board[i][col]) return true; } for(int i = 0; (row - i)&gt;=0 &amp;&amp; (col-i) &gt;= 0; i++) { if(board[row-i][col-i]) return true; } for(int i = 0; (row - i)&lt;=8 &amp;&amp; (col-i) &gt;= 0; i++) { if(board[row+i][col+i]) return true; } return false; } </code></pre>
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    1. PTQuestion
    1. This table or related slice is empty.
    1. USThomas Stefan Wire
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    1. CO`isSafe()` returns true when it is unsafe. Quite counter-intuitive...
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      1. POEight Queens C++ utilizing a Stack Backtracking
      1. UStimrau
    2. CO@timrau - counter-intuitive doesn't begin to describe it!!
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      1. POEight Queens C++ utilizing a Stack Backtracking
      1. USFloris
    3. COlolz Ill fix that
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      1. POEight Queens C++ utilizing a Stack Backtracking
      1. USThomas Stefan Wire
 

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