98 lines
3.6 KiB
C#
98 lines
3.6 KiB
C#
// Copyright 2010-2025 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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// [START import]
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using System;
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using Google.OrTools.ConstraintSolver;
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// [END import]
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public class CpIsFunCp
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{
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public static void Main(String[] args)
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{
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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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const int kBase = 10;
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// Decision variables.
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IntVar c = solver.MakeIntVar(1, kBase - 1, "C");
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IntVar p = solver.MakeIntVar(0, kBase - 1, "P");
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IntVar i = solver.MakeIntVar(1, kBase - 1, "I");
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IntVar s = solver.MakeIntVar(0, kBase - 1, "S");
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IntVar f = solver.MakeIntVar(1, kBase - 1, "F");
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IntVar u = solver.MakeIntVar(0, kBase - 1, "U");
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IntVar n = solver.MakeIntVar(0, kBase - 1, "N");
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IntVar t = solver.MakeIntVar(1, kBase - 1, "T");
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IntVar r = solver.MakeIntVar(0, kBase - 1, "R");
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IntVar e = solver.MakeIntVar(0, kBase - 1, "E");
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// Group variables in a vector so that we can use AllDifferent.
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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 (kBase < letters.Length)
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{
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throw new Exception("kBase < 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.Add(letters.AllDifferent());
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// CP + IS + FUN = TRUE
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solver.Add(p + s + n + kBase * (c + i + u) + kBase * kBase * f ==
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e + kBase * u + kBase * kBase * r + kBase * kBase * kBase * t);
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// [END constraints]
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// [START solve]
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int SolutionCount = 0;
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// Create the decision builder to search for solutions.
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DecisionBuilder db = 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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{
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Console.Write("C=" + c.Value() + " P=" + p.Value());
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Console.Write(" I=" + i.Value() + " S=" + s.Value());
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Console.Write(" F=" + f.Value() + " U=" + u.Value());
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Console.Write(" N=" + n.Value() + " T=" + t.Value());
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Console.Write(" R=" + r.Value() + " E=" + e.Value());
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Console.WriteLine();
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// Is CP + IS + FUN = TRUE?
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if (p.Value() + s.Value() + n.Value() + kBase * (c.Value() + i.Value() + u.Value()) +
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kBase * kBase * f.Value() !=
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e.Value() + kBase * u.Value() + kBase * kBase * r.Value() + kBase * kBase * kBase * t.Value())
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{
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throw new Exception("CP + IS + FUN != TRUE");
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}
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SolutionCount++;
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}
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solver.EndSearch();
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Console.WriteLine($"Number of solutions found: {SolutionCount}");
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// [END solve]
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}
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}
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// [END program]
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