Sort an array of 0,1 and 2. Dutch National Flag Problem

sort012.java

// Java program to sort an array of 0, 1 and 2
import java.io.*;

class countzot {

	// Sort the input array, the array is assumed to
	// have values in {0, 1, 2}
	static void sort012(int a[], int arr_size)
	{
		int lo = 0;
		int hi = arr_size - 1;
		int mid = 0,temp=0;
		while (mid <= hi)
		{
			switch (a[mid])
			{
			case 0:
			{
				if( a[lo] != a[mid]) {
				  temp = a[lo];
				  a[lo] = a[mid];
				  a[mid] = temp;
				}
				lo++;
				mid++;
				break;
			}
			case 1:
				mid++;
				break;
			case 2:
			{
			    if( a[mid] != a[hi]) {
    				temp = a[mid];
    				a[mid] = a[hi];
    				a[hi] = temp;
			    }	
				hi--;
				break;
			}
			}
		}
		System.out.println("middle " + mid);
		System.out.println("high   " + hi);
		System.out.println("low    " + lo);
	}

	/* Utility function to print array arr[] */
	static void printArray(int arr[], int arr_size)
	{
		int i;
		for (i = 0; i < arr_size; i++)
			System.out.print(arr[i]+" ");
		System.out.println("");
	}

	/*Driver function to check for above functions*/
	public static void main (String[] args)
	{
		int arr[] = {0, 1, 1,  2,  0, 1, 2};
		int arr_size = arr.length;
		sort012(arr, arr_size);
		System.out.println("Array after seggregation ");
		printArray(arr, arr_size);
	}
}