77 lines
2.4 KiB
Java
77 lines
2.4 KiB
Java
package hu.pj.alg;
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import hu.pj.obj.Item;
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import java.util.*;
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public class ContinuousKnapsack {
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protected List<Item> itemList = new ArrayList<Item>();
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protected double maxWeight = 0;
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protected double solutionWeight = 0;
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protected double profit = 0;
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protected boolean calculated = false;
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public ContinuousKnapsack() {}
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public ContinuousKnapsack(double _maxWeight) {
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setMaxWeight(_maxWeight);
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}
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public List<Item> calcSolution() {
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int n = itemList.size();
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setInitialStateForCalculation();
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if (n > 0 && maxWeight > 0) {
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Collections.sort(itemList);
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for (int i = 0; (maxWeight - solutionWeight) > 0.0 && i < n; i++) {
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Item item = itemList.get(i);
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if (item.getWeight() >= (maxWeight - solutionWeight)) {
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item.setInKnapsack(maxWeight - solutionWeight);
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solutionWeight = maxWeight;
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profit += item.getInKnapsack() / item.getWeight() * item.getValue();
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break;
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} else {
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item.setInKnapsack(item.getWeight());
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solutionWeight += item.getInKnapsack();
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profit += item.getValue();
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}
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}
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calculated = true;
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}
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return itemList;
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}
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// add an item to the item list
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public void add(String name, double weight, double value) {
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if (name.equals(""))
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name = "" + (itemList.size() + 1);
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itemList.add(new Item(name, weight, value));
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setInitialStateForCalculation();
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}
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public double getMaxWeight() {return maxWeight;}
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public double getProfit() {return profit;}
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public double getSolutionWeight() {return solutionWeight;}
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public boolean isCalculated() {return calculated;}
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public void setMaxWeight(double _maxWeight) {
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maxWeight = Math.max(_maxWeight, 0);
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}
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// set the member with name "inKnapsack" by all items:
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private void setInKnapsackByAll(double inKnapsack) {
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for (Item item : itemList)
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item.setInKnapsack(inKnapsack);
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}
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// set the data members of class in the state of starting the calculation:
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protected void setInitialStateForCalculation() {
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setInKnapsackByAll(-0.0001);
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calculated = false;
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profit = 0.0;
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solutionWeight = 0.0;
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}
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} // class
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