assigment_q3.rkt #lang racket In assignment_q3.rkt, write Scheme code to do the

Question

assigment_q3.rkt

#lang racket In assignment_q3.rkt, write Scheme code to do the following 12 marks each] A. Display in sorted order the contents of a binary search tree B. Return or #fif a given item is present or absent in a tree or not. The function C. Insert an item correctly into a list representing a binary search tree. Your function D. Take a list of items and insert them into a binary search tree. should take the item and a list representing a tree should take an item and a tree as inputs E. Implement a tree-sort algorithm. Your function should take a list of items and display them in sorted order Implement a higher order version of the tree-sort function that takes a list and a function that determines the sorted order. For example, write a version that sorts the list in ascending, descending and ascending based on last digit. F.

Explanation / Answer

package com;
public class DList<T> {
private DNode<T> header, trailer;
private int size;
public DList() {
size = 0;
header = new DNode<T>(null, null, null);
trailer = new DNode<T>(null, header, null);
header.setNext(trailer);
}
// utility methods
public int size() {
return size;
}
public boolean isEmpty() {
return size == 0;
}
// give clients access to nodes, but not to the header or trailer
public DNode<T> getFirst() throws Exception {
if (isEmpty())
throw new Exception("Empty");
return header.getNext();
}
public DNode<T> getLast() throws Exception {
if (isEmpty())
throw new Exception("Empty");
return trailer.getPrev();
}
public DNode<T> getNext(DNode<T> v) throws Exception {
DNode<T> ans = v.getNext();
if (ans == null || ans == trailer)
throw new Exception("No such node");
return ans;
}
public DNode<T> getPrev(DNode<T> v) throws Exception {
DNode<T> ans = v.getPrev();
if (ans == null || ans == header)
throw new Exception("No such node");
return ans;
}
// methods to change the list
public void addBefore(T d, DNode<T> v) {
DNode<T> u = v.getPrev();
DNode<T> x = new DNode<T>(d, u, v);
u.setNext(x);
v.setPrev(x);
size++;
}
public void addAfter(T d, DNode<T> v) {
DNode<T> w = v.getNext();
DNode<T> x = new DNode<T>(d, v, w);
v.setNext(x);
w.setPrev(x);
size++;
}
public void addFirst(T d) {
addAfter(d, header);
}
public void addLast(T d) {
addBefore(d, trailer);
}
public T remove(DNode<T> v) throws Exception {
if (v == header || v == trailer)
throw new Exception("Sentinel");
DNode<T> u = v.getPrev();
DNode<T> w = v.getNext();
w.setPrev(u);
u.setNext(w);
size--;
return v.getData();
}
// LinkedList testing methods:
public String toString() {
String ans = "";
DNode<T> n = header;
ans += "(H)<-->";
do {
n = n.getNext();
if (n == trailer)
ans += "(T)";
else
ans += (n.getData() + "<-->");
} while (n != trailer);
return ans;
}
}

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