Question

It is N queens problem please complete it

use this code

//***************************************************************

// D.S. Malik

//

// This class specifies the functions to solve the n-queens

// puzzle.

//***************************************************************

class nQueensPuzzle

{

public:

nQueensPuzzle(int queens = 8);

    //constructor

    //Postcondition: noOfSolutions = 0; noOfQueens = queens;

    // queensInRow is a pointer to the array

    // that store the n-tuple.

    // If no value is specified for the parameter queens,

    // the default value, which is 8, is assigned to it.

bool canPlaceQueen(int k, int i);

    //Function to determine whether a queen can be placed

    //in row k and column i.

    //Postcondition: returns true if a queen can be placed in

    // row k and column i; otherwise it returns false

void queensConfiguration(int k);

    //Function to determine all solutions to the n-queens

    //puzzle using backtracking.

    //The function is called with the value 0.

    //Postcondition: All n-tuples representing solutions of

    // n-queens puzzle are generated and printed.

void printConfiguration();

    //Function to output an n-tuple containing a solution

    //to the n-queens puzzle.

int solutionsCount();

    //Function to return the total number of solutions.

    //Postcondition: The value of noOfSolution is returned.

private:

int noOfSolutions;

int noOfQueens;

int *queensInRow;

};

#include <iostream>

#include <cmath>

#include "nQueenPuzzle.h"

using namespace std;

nQueensPuzzle::nQueensPuzzle()

{

    noOfQueens = 8;

    queensInColumn = new int[8];

    noOfSolutions = 0;

}

nQueensPuzzle::nQueensPuzzle(int queens)

{

    noOfQueens = queens;

    queensInColumn = new int[noOfQueens];

    noOfSolutions = 0;

}

bool nQueensPuzzle::canPlaceQueen(int k, int i)

{

    for(int j = 0; j < k; j++)

        if((queensInColumn[j] == i)

            || (abs(queensInColumn[j] - i) == abs(j-k)))

            return false;

    return true;

}

void nQueensPuzzle::queensConfiguration(int k)//, int queens)

{

    for(int i = 0; i < noOfQueens; i++)

    {

        if(canPlaceQueen(k, i))

        {

            queensInColumn[k] = i;

            if(k == noOfQueens - 1)

                printConfiguration();

            else

                queensConfiguration(k + 1);

        }

    }

}

void nQueensPuzzle::printConfiguration()

{

    noOfSolutions++;

    cout<<"(";

    for(int i = 0; i < noOfQueens - 1; i++)

        cout<<queensInColumn[i]<<", ";

    cout<<queensInColumn[noOfQueens - 1]<<")"<<endl;

}

int nQueensPuzzle::solutionsCount()

{

    return noOfSolutions;

}

Answer 1

Please give positive ratings for my efforts. Thanks.

PROGRAM

#include<stdio.h>
#include<math.h>

int board[20],count;
 
int main()
{
 int n,i,j;
 void queen(int row,int n);
 
 printf(" - N Queens Problem Using Backtracking -");
 printf("\n\nEnter number of Queens:");
 scanf("%d",&n);
 queen(1,n);
 return 0;
}
 
void print(int n)
{
 int i,j;
 printf("\n\nSolution %d:\n\n",++count);
 
 for(i=1;i<=n;++i)
  printf("\t%d",i);
 
 for(i=1;i<=n;++i)
 {
  printf("\n\n%d",i);
  for(j=1;j<=n;++j)
  {
   if(board[i]==j)
    printf("\tQ"); 
   else
    printf("\t-");
  }
 }
}
 
int place(int row,int column)
{
 int i;
 for(i=1;i<=row-1;++i)
 {
  if(board[i]==column)
   return 0;
  else
   if(abs(board[i]-column)==abs(i-row))
    return 0;
 }
 
 return 1;
}
 
void queen(int row,int n)
{
 int column;
 for(column=1;column<=n;++column)
 {
  if(place(row,column))
  {
   board[row]=column; 
   if(row==n) 
    print(n);
    else
    queen(row+1,n);
  }
 }
}