// Use First Child / Next Sibling tree representation
public class DemoNextSib {
  private static class NSNode<E> {
    E         data;
    NSNode<E> nextSib;
    NSNode<E> firstChild;
    public NSNode(E data,NSNode<E> nextSib,NSNode<E> firstChild) {
      this.data       = data;
      this.nextSib    = nextSib;
      this.firstChild = firstChild;
    }
  }
  private static void visit(NSNode node, int depth) {
    for (int i=0; i<depth; i++)
      System.out.print("      ");
    System.out.println(node.data);
  }
  private static void preorderTraverse(NSNode node, int depth) {
    visit(node, depth);
    preorderTraverseChildren(node, depth+1);
  }
  private static void preorderTraverseChildren(NSNode node, int depth) {
    NSNode n = node.firstChild;
    while (n != null) {
      preorderTraverse(n, depth);
      n = n.nextSib;
    }
  }       
  private static void postorderTraverse(NSNode node, int depth) {
    postorderTraverseChildren(node, depth+1);
    visit(node, depth);
  }
  private static void postorderTraverseChildren(NSNode node, int depth) {
    NSNode n = node.firstChild;
    while (n != null) {
      postorderTraverse(n, depth);
      n = n.nextSib;
    }
  }       
  public static void main(String[] arg) {
    NSNode<String> aaa=new NSNode<String>("AAA",null,null);
    NSNode<String> adc=new NSNode<String>("ADC",null,null);
    NSNode<String> ae =new NSNode<String>("AE", null,null);
    NSNode<String> adb=new NSNode<String>("ADB",adc, null);
    NSNode<String> ada=new NSNode<String>("ADA",adb, null);
    NSNode<String> ad =new NSNode<String>("AD", ae,  ada);
    NSNode<String> ac =new NSNode<String>("AC", ad, null);
    NSNode<String> ab =new NSNode<String>("AB", ac, null);
    NSNode<String> aa =new NSNode<String>("AA", ab, null);
    NSNode<String> a  =new NSNode<String>("A",  null,aa);
    System.out.printf("Preorder\n--------\n");
    preorderTraverse(a, 0);
    System.out.printf("\n\n---------------\n\n\nPostorder\n---------\n");
    postorderTraverse(a, 0);
  }
}
// Local Variables:
// c-basic-offset: 2
// compile-command: "javac DemoNextSib.java && java DemoNextSib"
// End: