Question

Complete the 8 queens 1 dimensional array program with backtracking in c+++. (don't use go to statement ) and please describe all the code statement and show the code in complier and also which can be copied. thank you very much

Answer 1

Hello i am providing the code fir 8 queens 1 dimensional array program with backtracking in c++ without any go to statement

please go through it once and if have any doubt please ask in comment i will be very happy to assist you

And please upvote if this helps you

 /**  Problem: EightQueens Problem
 *     The eight queens puzzle is the problem of placing eight chess queens on an 8×8 chessboard so 
 *     that no two queens attack each other. Thus, a solution requires that no two queens share the same row, 
 *         column, or diagonal. The eight queens puzzle is an example of the more general n-queens problem of placing
 *         n queens on an n×n chessboard, where solutions exist for all natural numbers n with the exception of 2 and 3.
 *  
 *      
 *  Input Format: 
 *      No Input is required, just run the program and it will display output arrangements of 8-queens.
 *
 *  OutPut Format:
 *      This program will out put all possible 8 queen arrangements on Chessboard, where no two queens attack  
 *      each other. i.e. this solution will output arrangements such that no two queens share the same row, column, 
 *      or diagonal. In the Output, 1 will represent queen and 0 non-queen.
 *
 * @Compiler version on which Program is Last Run before uploading to Github: Dev-C++ 5.4.1, Date: 1st July, 2013  
 * @author Gurpreet Singh
 */
// 8 queens using 1D array....with backtracking removing all gotos
    
    #include <iostream>
    #include<cstdlib>
    #include <cmath>
    using namespace std;

    bool ok(int q[], int col){
        for(int i=0;i<col;i++){ 
         if((q[i] == q[col]) || (abs(q[col] - q[i]) == (col - i))) 
         {   return false;
         }
       }
       return true;
    }//boolean function ends here
    
   void backtrack(int &col){
        col--;
        if(col==-1) exit(1);
       }//backtrack function ends here

   void print(int q[])
    {  static int count =0;
       count++;
       int i,j,board[8][8]={0};
       cout<<"#"<<count<<endl;
       for( i=0;i<8;i++)
       {
         board[q[i]][i]=1;           
       }
       
       for(i=0;i<8;i++)                 //final print board
        { for(j=0;j<8;j++)
             cout<<board[i][j]<<" ";
             
           cout<<endl;
        }
       
    }// Print function ends here

    int main()
    {
      int q[8]; q[0]=0;
      int c=1;
      // from_backtrack keeps track if we need to reset the row to the
      // top of the current colum or not.

      bool from_backtrack=false;
      // The outer loop keep looking for solutions
      // The program terminates from function backtrack
      // when we are forced to backtack into column -1
      while(1){
        while(c<8){ //this loop goes across columns
        // if we just returned from backtrack, use current value of row
        // otherwise get ready to start at the top of this column
         if(!from_backtrack) // we did not just return from backtrack
          q[c]=-1;   //check here
            from_backtrack=false;
              while(q[c]<8){ // place queen in this column
                q[c]++;
                  // if row=8, there is no valid square in this column
                 // so backtrack and continue the loop in the previous column
                 
                
                    while(q[c]==8)
                     { backtrack(c);
                       q[c]++;
                                  
                     }
                //if this position is ok, place the queen
                // and move on (break) to the next column,
                // otherwise keep looking in this column
                 
                  if(ok(q, c))
                     break;
                                   
              }// while q[c]<8
          c++; // placed ok, move to the next column
     }//while(c<8)
     // one complete solution found, print it.
     print(q); // board completed, print it out
     backtrack(c);
     from_backtrack=true;
    }//while(1)
   
}//main method

OUTPUT :

NOTE : There is total 92 boards in output can't add all here but adding some here thank you

Board 1-6 Board 87-92