91 lines
2.5 KiB
Java
91 lines
2.5 KiB
Java
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import java.io.*;
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import java.util.List;
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import java.util.ArrayList;
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/**
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* The class <code>Solver</code> is an implementation of a greedy algorithm to solve the knapsack problem.
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*
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*/
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public class Solver {
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/**
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* The main class
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*/
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public static void main(String[] args) {
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try {
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solve(args);
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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/**
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* Read the instance, solve it, and print the solution in the standard output
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*/
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public static void solve(String[] args) throws IOException {
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String fileName = null;
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// get the temp file name
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for(String arg : args){
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if(arg.startsWith("-file=")){
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fileName = arg.substring(6);
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}
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}
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if(fileName == null)
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return;
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// read the lines out of the file
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List<String> lines = new ArrayList<String>();
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BufferedReader input = new BufferedReader(new FileReader(fileName));
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try {
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String line = null;
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while (( line = input.readLine()) != null){
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lines.add(line);
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}
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}
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finally {
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input.close();
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}
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// parse the data in the file
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String[] firstLine = lines.get(0).split("\\s+");
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int items = Integer.parseInt(firstLine[0]);
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int capacity = Integer.parseInt(firstLine[1]);
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int[] values = new int[items];
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int[] weights = new int[items];
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for(int i=1; i < items+1; i++){
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String line = lines.get(i);
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String[] parts = line.split("\\s+");
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values[i-1] = Integer.parseInt(parts[0]);
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weights[i-1] = Integer.parseInt(parts[1]);
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}
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// a trivial greedy algorithm for filling the knapsack
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// it takes items in-order until the knapsack is full
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int value = 0;
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int weight = 0;
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int[] taken = new int[items];
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for(int i=0; i < items; i++){
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if(weight + weights[i] <= capacity){
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taken[i] = 1;
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value += values[i];
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weight += weights[i];
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} else {
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taken[i] = 0;
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}
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}
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// prepare the solution in the specified output format
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System.out.println(value+" 0");
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for(int i=0; i < items; i++){
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System.out.print(taken[i]+" ");
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}
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System.out.println("");
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}
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}
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