112 lines
4.2 KiB
Java
112 lines
4.2 KiB
Java
// Copyright 2010-2024 Google LLC
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// [START program]
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// Cryptarithmetic puzzle
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//
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// First attempt to solve equation CP + IS + FUN = TRUE
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// where each letter represents a unique digit.
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//
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// This problem has 72 different solutions in base 10.
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package com.google.ortools.constraintsolver.samples;
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// [START import]
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// [END import]
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import com.google.ortools.Loader;
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import com.google.ortools.constraintsolver.DecisionBuilder;
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import com.google.ortools.constraintsolver.IntVar;
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import com.google.ortools.constraintsolver.Solver;
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// [END import]
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/** Cryptarithmetic puzzle. */
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public final class CpIsFunCp {
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public static void main(String[] args) throws Exception {
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Loader.loadNativeLibraries();
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// Instantiate the solver.
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// [START solver]
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Solver solver = new Solver("CP is fun!");
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// [END solver]
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// [START variables]
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final int base = 10;
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// Decision variables.
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final IntVar c = solver.makeIntVar(1, base - 1, "C");
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final IntVar p = solver.makeIntVar(0, base - 1, "P");
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final IntVar i = solver.makeIntVar(1, base - 1, "I");
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final IntVar s = solver.makeIntVar(0, base - 1, "S");
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final IntVar f = solver.makeIntVar(1, base - 1, "F");
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final IntVar u = solver.makeIntVar(0, base - 1, "U");
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final IntVar n = solver.makeIntVar(0, base - 1, "N");
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final IntVar t = solver.makeIntVar(1, base - 1, "T");
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final IntVar r = solver.makeIntVar(0, base - 1, "R");
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final IntVar e = solver.makeIntVar(0, base - 1, "E");
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// Group variables in a vector so that we can use AllDifferent.
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final IntVar[] letters = new IntVar[] {c, p, i, s, f, u, n, t, r, e};
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// Verify that we have enough digits.
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if (base < letters.length) {
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throw new Exception("base < letters.Length");
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}
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// [END variables]
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// Define constraints.
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// [START constraints]
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solver.addConstraint(solver.makeAllDifferent(letters));
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// CP + IS + FUN = TRUE
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final IntVar sum1 =
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solver
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.makeSum(new IntVar[] {p, s, n,
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solver.makeProd(solver.makeSum(new IntVar[] {c, i, u}).var(), base).var(),
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solver.makeProd(f, base * base).var()})
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.var();
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final IntVar sum2 = solver
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.makeSum(new IntVar[] {e, solver.makeProd(u, base).var(),
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solver.makeProd(r, base * base).var(),
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solver.makeProd(t, base * base * base).var()})
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.var();
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solver.addConstraint(solver.makeEquality(sum1, sum2));
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// [END constraints]
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// [START solve]
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int countSolution = 0;
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// Create the decision builder to search for solutions.
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final DecisionBuilder db =
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solver.makePhase(letters, Solver.CHOOSE_FIRST_UNBOUND, Solver.ASSIGN_MIN_VALUE);
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solver.newSearch(db);
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while (solver.nextSolution()) {
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System.out.println("C=" + c.value() + " P=" + p.value());
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System.out.println(" I=" + i.value() + " S=" + s.value());
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System.out.println(" F=" + f.value() + " U=" + u.value());
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System.out.println(" N=" + n.value() + " T=" + t.value());
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System.out.println(" R=" + r.value() + " E=" + e.value());
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// Is CP + IS + FUN = TRUE?
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if (p.value() + s.value() + n.value() + base * (c.value() + i.value() + u.value())
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+ base * base * f.value()
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!= e.value() + base * u.value() + base * base * r.value()
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+ base * base * base * t.value()) {
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throw new Exception("CP + IS + FUN != TRUE");
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}
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countSolution++;
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}
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solver.endSearch();
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System.out.println("Number of solutions found: " + countSolution);
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// [END solve]
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}
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private CpIsFunCp() {}
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}
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// [END program]
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