Task: Knapsack problem_Continuous




Go: package main

import (
    "fmt"
    "sort"
)

type item struct {
    item   string
    weight float64
    price  float64
}

type items []item

var all = items{
    {"beef", 3.8, 36},
    {"pork", 5.4, 43},
    {"ham", 3.6, 90},
    {"greaves", 2.4, 45},
    {"flitch", 4.0, 30},
    {"brawn", 2.5, 56},
    {"welt", 3.7, 67},
    {"salami", 3.0, 95},
    {"sausage", 5.9, 98},
}


func (z items) Len() int      { return len(z) }
func (z items) Swap(i, j int) { z[i], z[j] = z[j], z[i] }
func (z items) Less(i, j int) bool {
    return z[i].price/z[i].weight > z[j].price/z[j].weight
}

func main() {
    left := 15.
    sort.Sort(all)
    for _, i := range all {
        if i.weight <= left {
            fmt.Println("take all the", i.item)
            if i.weight == left {
                return
            }
            left -= i.weight
        } else {
            fmt.Printf("take %.1fkg %s\n", left, i.item)
            return
        }
    }
}


Java: package hu.pj.alg.test;

import hu.pj.alg.ContinuousKnapsack;
import hu.pj.obj.Item;
import java.util.*;
import java.text.*;

public class ContinousKnapsackForRobber {
    final private double tolerance = 0.0005;

    public ContinousKnapsackForRobber() {
        ContinuousKnapsack cok = new ContinuousKnapsack(15); 

        
        cok.add("beef",     3.8, 36); 
        cok.add("pork",     5.4, 43); 
        cok.add("ham",      3.6, 90); 
        cok.add("greaves",  2.4, 45); 
        cok.add("flitch",   4.0, 30); 
        cok.add("brawn",    2.5, 56); 
        cok.add("welt",     3.7, 67); 
        cok.add("salami",   3.0, 95); 
        cok.add("sausage",  5.9, 98); 

        
        List<Item> itemList = cok.calcSolution();

        
        if (cok.isCalculated()) {
            NumberFormat nf  = NumberFormat.getInstance();

            System.out.println(
                "Maximal weight           = " +
                nf.format(cok.getMaxWeight()) + " kg"
            );
            System.out.println(
                "Total weight of solution = " +
                nf.format(cok.getSolutionWeight()) + " kg"
            );
            System.out.println(
                "Total value (profit)     = " +
                nf.format(cok.getProfit())
            );
            System.out.println();
            System.out.println(
                "You can carry the following materials " +
                "in the knapsack:"
            );
            for (Item item : itemList) {
                if (item.getInKnapsack() > tolerance) {
                    System.out.format(
                        "%1$-10s %2$-15s %3$-15s \n",
                        nf.format(item.getInKnapsack()) + " kg ",
                        item.getName(),
                        "(value = " + nf.format(item.getInKnapsack() *
                                                (item.getValue() / item.getWeight())) + ")"
                    );
                }
            }
        } else {
            System.out.println(
                "The problem is not solved. " +
                "Maybe you gave wrong data."
            );
        }

    }

    public static void main(String[] args) {
        new ContinousKnapsackForRobber();
    }

}