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1 /*
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2 * Copyright 2006 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 import java.util.*;
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26
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27 // Copyright 1996, Animorphic Systems
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28 // gri 28 Aug 92 / 15 Jan 93 / 8 Dec 95
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29
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30 class Queens {
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31
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32 static void try_i(boolean a[], boolean b[], boolean c[], int x[], int i) {
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33 int adj = 7;
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34
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35 for (int j = 1; j <= 8; j++) {
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36 if (b[j] && a[i+j] && c[adj+i-j]) {
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37 x[i] = j;
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38 b[j] = false;
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39 a[i+j] = false;
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40 c[adj+i-j] = false;
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41 if (i < 8) try_i(a, b, c, x, i+1);
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42 else print(x);
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43 b[j] = true;
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44 a[i+j] = true;
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45 c[adj+i-j] = true;
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46 }
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47 }
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48 }
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49
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50 public static void main(String s[]) {
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51 boolean a[] = new boolean[16+1];
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52 boolean b[] = new boolean[ 8+1];
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53 boolean c[] = new boolean[14+1];
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54 int x[] = new int[8+1];
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55 int adj = 7;
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56
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57 for (int i = -7; i <= 16; i++) {
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58 if (i >= 1 && i <= 8) b[i] = true;
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59 if (i >= 2) a[i] = true;
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60 if (i <= 7) c[adj+i] = true;
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61 }
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62
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63 x[0] = 0; // solution counter
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64
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65 try_i(a, b, c, x, 1);
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66 }
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67
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68 static void print(int x[]) {
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69 // first correct solution: A1 B5 C8 D6 E3 F7 G2 H4
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70
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71 char LF = (char)0xA;
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72 char CR = (char)0xD;
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73
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74 x[0]++;
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75 if (x[0] < 10)
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76 System.out.print(" ");
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77 System.out.print(x[0] + ". ");
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78 for (int i = 1; i <= 8; i++) {
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79 char p = (char)('A' + i - 1);
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80 System.out.print(p);
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81 System.out.print (x[i] + " ");
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82 }
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83 System.out.println();
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84 }
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85
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86 };
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