n-queen.cpp

#include<iostream>
#include<math.h>
using namespace std;

 int board[30],count=0;
 void queen(int);
 int placeQueen(int);
 void printSolution(int);

 int main()
 {
 int i,n;
 cout<<"Enter the number of Queens\n";
 cin>>n;
 queen(n);
 cout<<"\nTotal solutions = "<<count;

 return 0;
 }

int placeQueen(int pos)
 {
  int i;
  for(i=1;i<pos;i++)
  {
   if((board[i]==board[pos])||((abs(board[i]-board[pos])==abs(i-pos))))
   return 0;
 }
 return 1;
 }

 void printSolution(int n)
 {
 int i,j;
 count++;
 cout<<"\n\nSolution["<<count<<"]:\n";
  for(i=1;i<=n;i++)
 {
 for(j=1;j<=n;j++)
 {
  if(board[i]==j)
   cout<<"Q\t";
  else
   cout<<"*\t";
 }
  cout<<endl;
 }
 }
 void queen(int n)
 {
  int k=1;
  board[k]=0;
  while(k!=0)
 {
  board[k]=board[k]+1;
 while((board[k]<=n)&&!placeQueen(k))
  board[k]++;
  if(board[k]<=n)
 {
 if(k==n)
 printSolution(n);
 else
 {
 k++;
board[k]=0;
}
}
else
k--;
}
}