duke@435: /*
trims@1907:  * Copyright (c) 2006, 2008, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
duke@435: import java.util.*;
duke@435: 
duke@435: // Copyright 1996, Animorphic Systems
duke@435: // gri 28 Aug 92 / 15 Jan 93 / 8 Dec 95
duke@435: 
duke@435: class Queens {
duke@435: 
duke@435:   static void try_i(boolean a[], boolean b[], boolean c[], int x[], int i) {
duke@435:     int adj = 7;
duke@435: 
duke@435:     for (int j = 1; j <= 8; j++) {
duke@435:       if (b[j] && a[i+j] && c[adj+i-j]) {
duke@435:         x[i] = j;
duke@435:         b[j] = false;
duke@435:         a[i+j] = false;
duke@435:         c[adj+i-j] = false;
duke@435:         if (i < 8) try_i(a, b, c, x, i+1);
duke@435:         else print(x);
duke@435:         b[j] = true;
duke@435:         a[i+j] = true;
duke@435:         c[adj+i-j] = true;
duke@435:       }
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   public static void main(String s[]) {
duke@435:     boolean a[] = new boolean[16+1];
duke@435:     boolean b[] = new boolean[ 8+1];
duke@435:     boolean c[] = new boolean[14+1];
duke@435:     int     x[] = new int[8+1];
duke@435:     int adj = 7;
duke@435: 
duke@435:     for (int i = -7; i <= 16; i++) {
duke@435:       if (i >= 1 && i <= 8) b[i]     = true;
duke@435:       if (i >= 2)           a[i]     = true;
duke@435:       if (i <= 7)           c[adj+i] = true;
duke@435:     }
duke@435: 
duke@435:     x[0] = 0; // solution counter
duke@435: 
duke@435:     try_i(a, b, c, x, 1);
duke@435:   }
duke@435: 
duke@435:   static void print(int x[]) {
duke@435:     // first correct solution: A1 B5 C8 D6 E3 F7 G2 H4
duke@435: 
duke@435:     char LF = (char)0xA;
duke@435:     char CR = (char)0xD;
duke@435: 
duke@435:     x[0]++;
duke@435:     if (x[0] < 10)
duke@435:         System.out.print(" ");
duke@435:     System.out.print(x[0] + ". ");
duke@435:     for (int i = 1; i <= 8; i++) {
duke@435:       char p = (char)('A' + i - 1);
duke@435:       System.out.print(p);
duke@435:       System.out.print (x[i] + " ");
duke@435:     }
duke@435:     System.out.println();
duke@435:   }
duke@435: 
duke@435: };