Files
ortools-clone/examples/contrib/young_tableaux.cs
2022-09-05 17:38:11 +02:00

147 lines
3.7 KiB
C#

//
// Copyright 2012 Hakan Kjellerstrand
//
// 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.
using System;
using System.Collections;
using System.IO;
using System.Text.RegularExpressions;
using Google.OrTools.ConstraintSolver;
public class YoungTableaux
{
/**
*
* Implements Young tableaux and partitions.
* See http://www.hakank.org/or-tools/young_tableuax.py
*
*/
private static void Solve(int n)
{
Solver solver = new Solver("YoungTableaux");
//
// data
//
Console.WriteLine("n: {0}\n", n);
//
// Decision variables
//
IntVar[,] x = solver.MakeIntVarMatrix(n, n, 1, n + 1, "x");
IntVar[] x_flat = x.Flatten();
// partition structure
IntVar[] p = solver.MakeIntVarArray(n, 0, n + 1, "p");
//
// Constraints
//
// 1..n is used exactly once
for (int i = 1; i <= n; i++)
{
solver.Add(x_flat.Count(i, 1));
}
solver.Add(x[0, 0] == 1);
// row wise
for (int i = 0; i < n; i++)
{
for (int j = 1; j < n; j++)
{
solver.Add(x[i, j] >= x[i, j - 1]);
}
}
// column wise
for (int j = 0; j < n; j++)
{
for (int i = 1; i < n; i++)
{
solver.Add(x[i, j] >= x[i - 1, j]);
}
}
// calculate the structure (i.e. the partition)
for (int i = 0; i < n; i++)
{
IntVar[] b = new IntVar[n];
for (int j = 0; j < n; j++)
{
b[j] = x[i, j] <= n;
}
solver.Add(p[i] == b.Sum());
}
solver.Add(p.Sum() == n);
for (int i = 1; i < n; i++)
{
solver.Add(p[i - 1] >= p[i]);
}
//
// Search
//
DecisionBuilder db = solver.MakePhase(x_flat, Solver.CHOOSE_FIRST_UNBOUND, Solver.ASSIGN_MIN_VALUE);
solver.NewSearch(db);
while (solver.NextSolution())
{
Console.Write("p: ");
for (int i = 0; i < n; i++)
{
Console.Write(p[i].Value() + " ");
}
Console.WriteLine("\nx:");
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
long val = x[i, j].Value();
if (val <= n)
{
Console.Write(val + " ");
}
}
if (p[i].Value() > 0)
{
Console.WriteLine();
}
}
Console.WriteLine();
}
Console.WriteLine("\nSolutions: {0}", solver.Solutions());
Console.WriteLine("WallTime: {0}ms", solver.WallTime());
Console.WriteLine("Failures: {0}", solver.Failures());
Console.WriteLine("Branches: {0} ", solver.Branches());
solver.EndSearch();
}
public static void Main(String[] args)
{
int n = 5;
if (args.Length > 1)
{
n = Convert.ToInt32(args[1]);
}
Solve(n);
}
}