(JAVA) import java.util.*;
import javax.swing.*;
public class SuperQueen{
public static int N;
public static Set knightMove;
public static int noOfMoves = 0;
public static int max = 0;
public static void main(String args[]){
String in = JOptionPane.showInputDialog(null, "Enter the size of board");
N = Integer.parseInt(in);
int ans[] = new int[N];
Set col = new HashSet();
Set diag45 = new HashSet();
Set diag135 = new HashSet();
knightMove = new HashSet();
ans = queens(1, col, diag45, diag135);
System.out.println("Maximum No. of Super Queens for the " + N + "x" + N + "board:" + max); }
public static int[] queens(int k, Set col, Set diag45, Set diag135){
int sol[] = new int[N+1];
OrdSet oSet;
int j;
if(k < N+1){
if(noOfMoves == N){
System.out.println("Maximum No. of Moves for the " + N + "x" + N + "board:" + max);
System.exit(0); }
else{
for(j = 1; j < N+1; j++ ){
if(!col.contains(j) && !diag45.contains(j-k) && !diag135.contains(j+k) && chkPos(k, j)){
sol[k] = j;
col.add(j);
diag45.add(j-k);
diag135.add(j+k);
//Adding Knight Moves
oSet = new OrdSet(k, j);
knightMove.add(oSet);
noOfMoves++;
if(max < noOfMoves)
max = noOfMoves;
queens(k+1, col, diag45, diag135);
diag45.remove(j-k);
diag135.remove(j+k);
col.remove(j);
knightMove.remove(oSet);
noOfMoves--; } }
queens(k+1, col, diag45, diag135); } }
return sol; }
public static boolean chkPos(int x, int y){
Iterator it = knightMove.iterator();
boolean retValue = true;
if(knightMove.size() == 0)
return true;
while(it.hasNext()){
OrdSet oSet = (OrdSet)it.next();
if(Math.abs(oSet.getX()-x) < 3.0 && Math.abs(oSet.getY()-y) < 3.0){
retValue = false; } }
return retValue; }
public static class OrdSet{
private int X;
private int Y;
OrdSet(){
X = 0;
Y = 0; }
OrdSet(int x, int y){
X = x;
Y = y; }
public int getX(){
return X; }
public int getY(){
return Y; } } }