import java.util.ArrayList;

public class PermuteInt {
  public static ArrayList<ArrayList<Integer>>
    permutations(ArrayList<Integer> list) {
      ArrayList<ArrayList<Integer>> permuted_list =
        new ArrayList<ArrayList<Integer>>();

      if(list.size() < 2) {
        permuted_list.add(list);
        return permuted_list;
      }

      for(int i=0;i<list.size();i++) {
        // First create a copy of the list with the
        // ith element removed
        ArrayList<Integer> shorter_list =
          new ArrayList<Integer>();
        for(int j=0;j<list.size();j++) {
          if(i != j)
            shorter_list.add(list.get(j));
        }
        // Now iterate through all permutations of
        // this shorter list
        for(ArrayList<Integer> ilist : permutations(shorter_list)) {
          // Add back the element we took out to
          // make the shorter list the right length
          ilist.add(list.get(i));
          // add the list to the list of permuted lists
          permuted_list.add(ilist);
        }
      }
      return permuted_list;
    }

  public static void main(String[] args) {
    ArrayList<Integer> list = new ArrayList<Integer>();
    for(int i : new int[]{1,2,3,4}) {
      list.add(i);
    }
    for(ArrayList<Integer> permuted_list : permutations(list)) {
      System.out.println(permuted_list);
    }
  }
}