141 lines
3.8 KiB
Java
141 lines
3.8 KiB
Java
// Copyright 2011 Hakan Kjellerstrand hakank@gmail.com
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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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package com.google.ortools.contrib;
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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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import java.io.*;
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import java.text.*;
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import java.util.*;
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public class YoungTableaux {
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/**
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* Implements Young tableaux and partitions. See
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* http://www.hakank.org/google_or_tools/young_tableuax.py
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*/
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private static void solve(int n) {
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Solver solver = new Solver("YoungTableaux");
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System.out.println("n: " + n);
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//
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// variables
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//
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IntVar[][] x = new IntVar[n][n];
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IntVar[] x_flat = new IntVar[n * n];
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for (int i = 0; i < n; i++) {
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for (int j = 0; j < n; j++) {
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x[i][j] = solver.makeIntVar(1, n + 1, "x[" + i + "," + j + "]");
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x_flat[i * n + j] = x[i][j];
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}
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}
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// partition structure
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IntVar[] p = solver.makeIntVarArray(n, 0, n + 1, "p");
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//
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// constraints
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//
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// 1..n is used exactly once
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for (int i = 1; i <= n; i++) {
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solver.addConstraint(solver.makeCount(x_flat, i, 1));
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}
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solver.addConstraint(solver.makeEquality(x[0][0], 1));
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// row wise
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for (int i = 0; i < n; i++) {
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for (int j = 1; j < n; j++) {
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solver.addConstraint(solver.makeGreaterOrEqual(x[i][j], x[i][j - 1]));
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}
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}
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// column wise
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for (int j = 0; j < n; j++) {
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for (int i = 1; i < n; i++) {
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solver.addConstraint(solver.makeGreaterOrEqual(x[i][j], x[i - 1][j]));
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}
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}
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// calculate the structure (i.e. the partition)
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for (int i = 0; i < n; i++) {
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IntVar[] b = new IntVar[n];
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for (int j = 0; j < n; j++) {
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b[j] = solver.makeIsLessOrEqualCstVar(x[i][j], n);
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}
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solver.addConstraint(solver.makeEquality(p[i], solver.makeSum(b).var()));
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}
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solver.addConstraint(solver.makeEquality(solver.makeSum(p).var(), n));
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for (int i = 1; i < n; i++) {
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solver.addConstraint(solver.makeGreaterOrEqual(p[i - 1], p[i]));
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}
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//
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// search
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//
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DecisionBuilder db =
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solver.makePhase(x_flat, solver.CHOOSE_FIRST_UNBOUND, solver.ASSIGN_MIN_VALUE);
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solver.newSearch(db);
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//
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// output
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//
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while (solver.nextSolution()) {
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System.out.print("p: ");
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for (int i = 0; i < n; i++) {
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System.out.print(p[i].value() + " ");
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}
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System.out.println("\nx:");
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for (int i = 0; i < n; i++) {
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for (int j = 0; j < n; j++) {
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long val = x[i][j].value();
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if (val <= n) {
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System.out.print(val + " ");
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}
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}
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if (p[i].value() > 0) {
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System.out.println();
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}
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}
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System.out.println();
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}
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solver.endSearch();
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// Statistics
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System.out.println();
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System.out.println("Solutions: " + solver.solutions());
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System.out.println("Failures: " + solver.failures());
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System.out.println("Branches: " + solver.branches());
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System.out.println("Wall time: " + solver.wallTime() + "ms");
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}
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public static void main(String[] args) throws Exception {
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Loader.loadNativeLibraries();
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int n = 5;
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if (args.length > 0) {
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n = Integer.parseInt(args[0]);
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}
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YoungTableaux.solve(n);
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}
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}
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