102 lines
3.1 KiB
Java
102 lines
3.1 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.OptimizeVar;
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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 CoinsGrid {
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/** Solves the Coins Grid problem. See http://www.hakank.org/google_or_tools/coins_grid.py */
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private static void solve() {
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Solver solver = new Solver("CoinsGrid");
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// data
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int n = 5; // 31;
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int c = 2; // 14;
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// variables
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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(0, 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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// constraints
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// sum row/columns == c
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for (int i = 0; i < n; i++) {
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IntVar[] row = new IntVar[n];
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IntVar[] col = new IntVar[n];
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for (int j = 0; j < n; j++) {
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row[j] = x[i][j];
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col[j] = x[j][i];
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}
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solver.addConstraint(solver.makeSumEquality(row, c));
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solver.addConstraint(solver.makeSumEquality(col, c));
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}
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// quadratic horizonal distance
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IntVar[] obj_tmp = 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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obj_tmp[i * n + j] = solver.makeProd(x[i][j], (i - j) * (i - j)).var();
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}
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}
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IntVar obj_var = solver.makeSum(obj_tmp).var();
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// objective
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OptimizeVar obj = solver.makeMinimize(obj_var, 1);
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// search
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DecisionBuilder db =
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solver.makePhase(x_flat, solver.CHOOSE_FIRST_UNBOUND, solver.ASSIGN_MAX_VALUE);
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solver.newSearch(db, obj);
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// output
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while (solver.nextSolution()) {
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System.out.println("obj_var: " + obj_var.value());
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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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System.out.print(x[i][j].value() + " ");
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}
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System.out.println();
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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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CoinsGrid.solve();
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}
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}
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