Knapsack Problem

KnapsackProblem.java

import java.text.DecimalFormat;


/*
    1   2   3   4   5   6   7
    10  5   15  7   6   18  3
    2   3   5   7   1   4   1
    5   1.6 3   0   6   4.5 3

    5   1   14  1 X 6
    1   2   12  2 X 5
    6   4   8   4 X 4.5
    3   5   3   5 X 3
    7   1   2   1 X 3
    2   2   0   2 X 1.67
                55.2
 */

public class KnapsackProblem {
    public static void main(String[] args) {
        int[] weights = {2, 3, 5, 7, 1, 4, 1};
        int[] profits = {10, 5, 15, 7, 6, 18, 3};

        System.out.println(getMaxProfit(weights, profits, 15, 7));
    }

    private static double getMaxProfit(int[] weights, int[] profits, int maxCapacity, int n) {
        double[] profitWeightRatios = new double[n];

        for (int i = 0; i < n; i++) {
            profitWeightRatios[i] = Double.parseDouble(new DecimalFormat("#.##")
                    .format((double) profits[i] / (double) weights[i]));
        }

        for (int i = 0; i < n - 1; i++) {
            for (int j = (i + 1); j < n; j++) {
                if (profitWeightRatios[i] >= profitWeightRatios[j]) {
                    swap(profitWeightRatios, i, j);
                    swap(weights, i, j);
                }
            }
        }

        double maxProfit = 0;
        for (int i = n - 1; i >= 0; i--) {
            if (maxCapacity == 0) {
                break;
            }

            if (maxCapacity - weights[i] < 0) {
                maxProfit += (double) maxCapacity * profitWeightRatios[i];
                maxCapacity = 0;
            } else {
                maxCapacity -= weights[i];
                maxProfit += (double) weights[i] * profitWeightRatios[i];
            }
        }

        return maxProfit;
    }

    private static void swap(double[] arr, int a, int b) {
        double temp = arr[a];
        arr[a] = arr[b];
        arr[b] = temp;
    }

    private static void swap(int[] arr, int a, int b) {
        int temp = arr[a];
        arr[a] = arr[b];
        arr[b] = temp;
    }
}