Inverse Permutation java in pgm

InversePermutation.java

public class InversePermutation

{

   public static void main(String[] args)

{

   int N = args.length;

      int[] a    = new int[N];

      for (int i = 0; i < N; i++)

         a[i] = Integer.parseInt(args[i]);

      boolean[] exists = new boolean[N];

      for (int i = 0; i < N; i++)

      {

         if (a[i] < 0 || a[i] >= N || exists[a[i]])

             throw new RuntimeException("Input is not a permutation.");

         exists[a[i]] = true;

      }

      int[] ainv = new int[N];

      for (int i = 0; i < N; i++)

         ainv[a[i]] = i; 

        for (int i = 0; i < N; i++)

         System.out.print(ainv[i] + " ");

      System.out.println();

   }

}