126 lines
4.2 KiB
C#
126 lines
4.2 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.Collections.Generic;
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using System.Linq;
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using Google.OrTools.ConstraintSolver;
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public class SecretSanta
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{
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/**
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*
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* Secret Santa problem in Google CP Solver.
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*
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* From Ruby Quiz Secret Santa
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* http://www.rubyquiz.com/quiz2.html
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* """
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* Honoring a long standing tradition started by my wife's dad, my friends
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* all play a Secret Santa game around Christmas time. We draw names and
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* spend a week sneaking that person gifts and clues to our identity. On the
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* last night of the game, we get together, have dinner, share stories, and,
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* most importantly, try to guess who our Secret Santa was. It's a crazily
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* fun way to enjoy each other's company during the holidays.
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*
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* To choose Santas, we use to draw names out of a hat. This system was
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* tedious, prone to many 'Wait, I got myself...' problems. This year, we
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* made a change to the rules that further complicated picking and we knew
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* the hat draw would not stand up to the challenge. Naturally, to solve
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* this problem, I scripted the process. Since that turned out to be more
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* interesting than I had expected, I decided to share.
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*
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* This weeks Ruby Quiz is to implement a Secret Santa selection script.
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* * Your script will be fed a list of names on STDIN.
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* ...
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* Your script should then choose a Secret Santa for every name in the list.
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* Obviously, a person cannot be their own Secret Santa. In addition, my
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* friends no longer allow people in the same family to be Santas for each
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* other and your script should take this into account.
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* """
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*
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* Comment: This model skips the file input and mail parts. We
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* assume that the friends are identified with a number from 1..n,
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* and the families is identified with a number 1..num_families.
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*
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* Also see http://www.hakank.org/or-tools/secret_santa.py
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* Also see http://www.hakank.org/or-tools/secret_santa2.cs
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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("SecretSanta");
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int[] family = { 1, 1, 1, 1, 2, 3, 3, 3, 3, 3, 4, 4 };
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int n = family.Length;
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Console.WriteLine("n = {0}", n);
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IEnumerable<int> RANGE = Enumerable.Range(0, n);
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//
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// Decision variables
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//
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IntVar[] x = solver.MakeIntVarArray(n, 0, n - 1, "x");
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//
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// Constraints
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//
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solver.Add(x.AllDifferent());
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// Can't be one own"s Secret Santa
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// (i.e. ensure that there are no fix-point in the array.)
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foreach (int i in RANGE)
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{
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solver.Add(x[i] != i);
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}
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// No Secret Santa to a person in the same family
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foreach (int i in RANGE)
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{
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solver.Add(solver.MakeIntConst(family[i]) != family.Element(x[i]));
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}
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//
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// Search
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//
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DecisionBuilder db = solver.MakePhase(x, Solver.INT_VAR_SIMPLE, Solver.INT_VALUE_SIMPLE);
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solver.NewSearch(db);
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while (solver.NextSolution())
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{
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Console.Write("x: ");
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foreach (int i in RANGE)
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{
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Console.Write(x[i].Value() + " ");
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}
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Console.WriteLine();
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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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