123 lines
3.2 KiB
C#
123 lines
3.2 KiB
C#
//
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// Copyright 2012 Hakan Kjellerstrand
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//
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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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using System;
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using System.Collections;
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using System.IO;
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using System.Linq;
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using System.Text.RegularExpressions;
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using Google.OrTools.ConstraintSolver;
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public class DudeneyNumbers
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{
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private static Constraint ToNum(IntVar[] a, IntVar num, int bbase) {
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int len = a.Length;
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IntVar[] tmp = new IntVar[len];
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for(int i = 0; i < len; i++) {
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tmp[i] = (a[i]*(int)Math.Pow(bbase,(len-i-1))).Var();
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}
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return tmp.Sum() == num;
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}
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/**
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*
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* Dudeney numbers
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* From Pierre Schaus blog post
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* Dudeney number
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* http://cp-is-fun.blogspot.com/2010/09/test-python.html
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* """
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* I discovered yesterday Dudeney Numbers
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* A Dudeney Numbers is a positive integer that is a perfect cube such that the sum
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* of its decimal digits is equal to the cube root of the number. There are only six
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* Dudeney Numbers and those are very easy to find with CP.
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* I made my first experience with google cp solver so find these numbers (model below)
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* and must say that I found it very convenient to build CP models in python!
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* When you take a close look at the line:
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* solver.Add(sum([10**(n-i-1)*x[i] for i in range(n)]) == nb)
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* It is difficult to argue that it is very far from dedicated
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* optimization languages!
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* """
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*
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* Also see: http://en.wikipedia.org/wiki/Dudeney_number
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*
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*/
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private static void Solve()
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{
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Solver solver = new Solver("DudeneyNumbers");
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//
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// data
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//
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int n = 6;
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//
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// Decision variables
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//
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IntVar[] x = solver.MakeIntVarArray(n, 0, 9, "x");
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IntVar nb = solver.MakeIntVar(3, (int)Math.Pow(10,n), "nb");
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IntVar s = solver.MakeIntVar(1,9*n+1,"s");
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//
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// Constraints
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//
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solver.Add(nb == s*s*s);
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solver.Add(x.Sum() == s);
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// solver.Add(ToNum(x, nb, 10));
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// alternative
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solver.Add((from i in Enumerable.Range(0, n)
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select (x[i]*(int)Math.Pow(10,n-i-1)).Var()).
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ToArray().Sum() == nb);
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//
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// Search
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//
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DecisionBuilder db = solver.MakePhase(x,
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Solver.INT_VAR_DEFAULT,
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Solver.INT_VALUE_DEFAULT);
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solver.NewSearch(db);
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while (solver.NextSolution()) {
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Console.WriteLine(nb.Value());
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}
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Console.WriteLine("\nSolutions: {0}", solver.Solutions());
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Console.WriteLine("WallTime: {0}ms", solver.WallTime());
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Console.WriteLine("Failures: {0}", solver.Failures());
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Console.WriteLine("Branches: {0} ", solver.Branches());
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solver.EndSearch();
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}
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public static void Main(String[] args)
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{
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Solve();
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}
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}
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