pigeonhole_sort.java

import java.lang.*;
import java.util.*;

public class pigeonhole_sort
{
    public static void pigeonhole_sort(int arr[],
                                           int n)
    {
        int min = arr[0];
        int max = arr[0];
        int range, i, j, index;

        for(int a=0; a<n; a++)
        {
            if(arr[a] > max)
                max = arr[a];
            if(arr[a] < min)
                min = arr[a];
        }

        range = max - min + 1;
        int[] phole = new int[range];
        Arrays.fill(phole, 0);

        for(i = 0; i<n; i++)
            phole[arr[i] - min]++;


        index = 0;

        for(j = 0; j<range; j++)
            while(phole[j]-->0)
                arr[index++]=j+min;

    }

    public static void main(String[] args)
    {
        GFG sort = new GFG();
        int[] arr = {8, 3, 2, 7, 4, 6, 8};

        System.out.print("Sorted order is : ");

        sort.pigeonhole_sort(arr,arr.length);

        for(int i=0 ; i<arr.length ; i++)
            System.out.print(arr[i] + " ");
    }

}