programming-examples/java/Computational_Geometry_Problems/Java Program to Implement First Fit Decreasing for 1-D Objects and M Bins.java

/*This is a Java Program to implement First fit Decreasing Bin Packing algorithm. The First Fit Decreasing (FFD) strategy, operates by first sorting the items to be inserted in decreasing order by their sizes, and then inserting each item into the first bin in the list with sufficient remaining space.*/

//This is a java program to implement first fit decreasing for 1D objects using M bins
import java.util.Scanner;

public class First_Fit_Decreasing_Bin_Packing
{
    public static void main(String args[])
    {
        System.out
        .println("BIN - PACKING Algorithm 1D Objects(First Fit Decreasing)");
        System.out.println("Enter the number of items in Set: ");
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println("Enter " + n + " items:");
        int[] a = new int[n];
        for (int i = 0; i < n; i++)
            a[i] = sc.nextInt();
        System.out.println("Enter the bin size: ");
        int size = sc.nextInt();
        int[] sequence = sort(a);
        binPacking(sequence, size, n);
        sc.close();
    }

    public static void binPacking(int[] a, int size, int n)
    {
        int binCount = 0;
        int[] binValues = new int[n];
        for (int i = 0; i < binValues.length; i++)
            binValues[i] = size;
        for (int i = 0; i < n; i++)
            for (int j = 0; j < binValues.length; j++)
                {
                    if (binValues[j] - a[i] >= 0)
                        {
                            binValues[j] -= a[i];
                            break;
                        }
                }
        for (int i = 0; i < binValues.length; i++)
            if (binValues[i] != size)
                binCount++;
        System.out
        .println("Number of bins required using first fit decreasing algorithm is:"
                 + binCount);
    }

    static int[] sort(int[] sequence)
    {
        // Bubble Sort descending order
        for (int i = 0; i < sequence.length; i++)
            for (int j = 0; j < sequence.length - 1; j++)
                if (sequence[j] < sequence[j + 1])
                    {
                        sequence[j] = sequence[j] + sequence[j + 1];
                        sequence[j + 1] = sequence[j] - sequence[j + 1];
                        sequence[j] = sequence[j] - sequence[j + 1];
                    }
        return sequence;
    }
}

/*
BIN - PACKING Algorithm for 1D Objects(First Fit Decreasing)
Enter the number of items in Set:
9
Enter 9 items:
4
1
2
5
3
2
3
6
3
Enter the bin size:
6
Number of bins required using first fit decreasing algorithm is:5