92 lines
2.8 KiB
Java
92 lines
2.8 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.*;
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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 Diet {
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/** Solves the Diet problem. See http://www.hakank.org/google_or_tools/diet1.py */
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private static void solve() {
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Solver solver = new Solver("Diet");
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int n = 4;
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int[] price = {50, 20, 30, 80}; // in cents
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// requirements for each nutrition type
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int[] limits = {500, 6, 10, 8};
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// nutritions for each product
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int[] calories = {400, 200, 150, 500};
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int[] chocolate = {3, 2, 0, 0};
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int[] sugar = {2, 2, 4, 4};
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int[] fat = {2, 4, 1, 5};
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//
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// Variables
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//
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IntVar[] x = solver.makeIntVarArray(n, 0, 100, "x");
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IntVar cost = solver.makeScalProd(x, price).var();
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//
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// Constraints
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//
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solver.addConstraint(solver.makeScalProdGreaterOrEqual(x, calories, limits[0]));
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solver.addConstraint(solver.makeScalProdGreaterOrEqual(x, chocolate, limits[1]));
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solver.addConstraint(solver.makeScalProdGreaterOrEqual(x, sugar, limits[2]));
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solver.addConstraint(solver.makeScalProdGreaterOrEqual(x, fat, limits[3]));
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//
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// Objective
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//
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OptimizeVar obj = solver.makeMinimize(cost, 1);
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//
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// Search
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//
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DecisionBuilder db = solver.makePhase(x, solver.CHOOSE_PATH, solver.ASSIGN_MIN_VALUE);
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solver.newSearch(db, obj);
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while (solver.nextSolution()) {
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System.out.println("cost: " + cost.value());
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System.out.print("x: ");
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for (int i = 0; i < n; i++) {
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System.out.print(x[i].value() + " ");
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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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Diet.solve();
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}
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}
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