8queensnew.cpp

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

int chess_board[20], count;

int display(int);
void queen_function(int, int);
int placeholder(int, int);

void queen_function(int row_value, int limit)
{
      int column_value;
      for(column_value = 1; column_value <= limit; column_value++)
      {
            if(placeholder(row_value, column_value))
            {
                  chess_board[row_value] = column_value;
                  if(row_value == limit)
                  {
                        display(limit);
                  }
                  else
                  {
                        queen_function(row_value + 1, limit);
                  }
            }
      }
}

int placeholder(int row_value, int column_value)
{
      int count;
      for(count = 1; count <= row_value - 1; count++)
      {
            if(chess_board[count] == column_value)
            {
                  return 0;
            }
            else
            {
                  if(abs(chess_board[count] - column_value) == abs(count - row_value))
                  {
                        return 0;
                  }
            }
      }
      return 1;
}

int display(int limit)
{
      int m, n;
      printf("\n\n\tPossible Solution %d:\n\n", ++count);
      for(m = 1; m <= limit; m++)
      {
            printf("\t[%d]", m);
      }
      for(m = 1; m <= limit; m++)
      {
            printf("\n\n[%d]", m);
            for(n = 1; n <= limit; n++)
            {
                  if(chess_board[m] == n)
                  {
                        printf("\tQ");
                  }
                  else
                  {
                        printf("\t*");
                  }
            }
      }
}

int main()
{
      int limit;
      printf("\nEnter Number of Queens:\t");
      scanf("%d", &limit);
      if(limit <= 3)
      {
            printf("\nNumber should be greater than 3 to form a Matrix\n");
      }
      else
      {
            queen_function(1, limit);
      }
      printf("\n\n");
      return 0;
}