Crossword.java

// Copyright 2011 Hakan Kjellerstrand hakank@gmail.com
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import com.google.ortools.constraintsolver.DecisionBuilder;
import com.google.ortools.constraintsolver.IntVar;
import com.google.ortools.constraintsolver.Solver;
import java.io.*;
import java.text.*;
import java.util.*;

public class Crossword {

  static {
    System.loadLibrary("jniortools");
  }

  /** Solving a simple crossword. See http://www.hakank.org/google_or_tools/crossword2.py */
  private static void solve() {

    Solver solver = new Solver("Crossword");

    //
    // data
    //
    String[] alpha = {
      "_", "a", "b", "c", "d", "e", "f",
      "g", "h", "i", "j", "k", "l", "m",
      "n", "o", "p", "q", "r", "s", "t",
      "u", "v", "w", "x", "y", "z"
    };

    int a = 1;
    int b = 2;
    int c = 3;
    int d = 4;
    int e = 5;
    int f = 6;
    int g = 7;
    int h = 8;
    int i = 9;
    int j = 10;
    int k = 11;
    int l = 12;
    int m = 13;
    int n = 14;
    int o = 15;
    int p = 16;
    int q = 17;
    int r = 18;
    int s = 19;
    int t = 20;
    int u = 21;
    int v = 22;
    int w = 23;
    int x = 24;
    int y = 25;
    int z = 26;

    int num_words = 15;
    int word_len = 5;

    int[][] AA = {
      {h, o, s, e, s}, //  HOSES
      {l, a, s, e, r}, //  LASER
      {s, a, i, l, s}, //  SAILS
      {s, h, e, e, t}, //  SHEET
      {s, t, e, e, r}, //  STEER
      {h, e, e, l, 0}, //  HEEL
      {h, i, k, e, 0}, //  HIKE
      {k, e, e, l, 0}, //  KEEL
      {k, n, o, t, 0}, //  KNOT
      {l, i, n, e, 0}, //  LINE
      {a, f, t, 0, 0}, //  AFT
      {a, l, e, 0, 0}, //  ALE
      {e, e, l, 0, 0}, //  EEL
      {l, e, e, 0, 0}, //  LEE
      {t, i, e, 0, 0}
    }; //  TIE

    int num_overlapping = 12;
    int[][] overlapping = {
      {0, 2, 1, 0}, //  s
      {0, 4, 2, 0}, //  s
      {3, 1, 1, 2}, //  i
      {3, 2, 4, 0}, //  k
      {3, 3, 2, 2}, //  e
      {6, 0, 1, 3}, //  l
      {6, 1, 4, 1}, //  e
      {6, 2, 2, 3}, //  e
      {7, 0, 5, 1}, //  l
      {7, 2, 1, 4}, //  s
      {7, 3, 4, 2}, //  e
      {7, 4, 2, 4}
    }; //  r

    int N = 8;

    //
    // variables
    //
    IntVar[][] A = new IntVar[num_words][word_len];
    IntVar[] A_flat = new IntVar[num_words * word_len];
    // for labeling on A and E
    IntVar[] all = new IntVar[(num_words * word_len) + N];

    for (int I = 0; I < num_words; I++) {
      for (int J = 0; J < word_len; J++) {
        A[I][J] = solver.makeIntVar(0, 26, "A[" + I + "," + J + "]");
        A_flat[I * word_len + J] = A[I][J];
        all[I * word_len + J] = A[I][J];
      }
    }

    IntVar[] E = solver.makeIntVarArray(N, 0, num_words, "E");
    for (int I = 0; I < N; I++) {
      all[num_words * word_len + I] = E[I];
    }

    //
    // constraints
    //
    solver.addConstraint(solver.makeAllDifferent(E));

    for (int I = 0; I < num_words; I++) {
      for (int J = 0; J < word_len; J++) {
        solver.addConstraint(solver.makeEquality(A[I][J], AA[I][J]));
      }
    }

    for (int I = 0; I < num_overlapping; I++) {
      solver.addConstraint(
          solver.makeEquality(
              solver
                  .makeElement(
                      A_flat,
                      solver
                          .makeSum(
                              solver.makeProd(E[overlapping[I][0]], word_len).var(),
                              overlapping[I][1])
                          .var())
                  .var(),
              solver
                  .makeElement(
                      A_flat,
                      solver
                          .makeSum(
                              solver.makeProd(E[overlapping[I][2]], word_len).var(),
                              overlapping[I][3])
                          .var())
                  .var()));
    }

    //
    // search
    //
    DecisionBuilder db = solver.makePhase(all, solver.INT_VAR_DEFAULT, solver.INT_VALUE_DEFAULT);

    solver.newSearch(db);

    //
    // output
    //
    while (solver.nextSolution()) {
      System.out.println("E:");
      for (int ee = 0; ee < N; ee++) {
        int e_val = (int) E[ee].value();
        System.out.print(ee + ": (" + e_val + ") ");
        for (int ii = 0; ii < word_len; ii++) {
          System.out.print(alpha[(int) A[ee][ii].value()]);
        }
        System.out.println();
      }

      System.out.println();
    }

    solver.endSearch();

    // Statistics
    System.out.println();
    System.out.println("Solutions: " + solver.solutions());
    System.out.println("Failures: " + solver.failures());
    System.out.println("Branches: " + solver.branches());
    System.out.println("Wall time: " + solver.wallTime() + "ms");
  }

  public static void main(String[] args) throws Exception {

    Crossword.solve();
  }
}