import java.util.Iterator; import java.util.NoSuchElementException; public inter
ID: 3546827 • Letter: I
Question
import java.util.Iterator;
import java.util.NoSuchElementException;
public interface DictionaryADT<K,V> {
// Returns true if the dictionary has an object identified by
// key in it, otherwise false.
public boolean contains(K key);
// Adds the given key/value pair to the dictionary. Returns
// false if the dictionary is full, or if the key is a duplicate.
// Returns true if addition succeeded.
public boolean insert(K key, V value);
// Deletes the key/value pair identified by the key parameter.
// Returns true if the key/value pair was found and removed,
// otherwise false.
public boolean remove(K key);
// Returns the value associated with the parameter key. Returns
// null if the key is not found or the dictionary is empty.
public V getValue(K key);
// Returns the key associated with the parameter value. Returns
// null if the value is not found in the dictionary. If more
// than one key exists that matches the given value, returns the
// first one found.
public K getKey(V value);
// Returns the number of key/value pairs currently stored
// in the dictionary
public int size();
// Returns true if the dictionary is at max capacity
public boolean isFull();
// Returns true if the dictionary is empty
public boolean isEmpty();
// Returns the Dictionary object to an empty state.
public void clear();
// Returns an Iterator of the keys in the dictionary, in ascending
// sorted order. The iterator must be fail-fast.
public Iterator<K> keys();
// Returns an Iterator of the values in the dictionary. The
// order of the values must match the order of the keys.
// The iterator must be fail-fast.
public Iterator<V> values();
}
package data_structures;
import java.util.Iterator;
import java.util.NoSuchElementException;
public class LinkedListDS<E> implements ListADT<E> {
private Node<E> head,tail;
private int currentSize;
public LinkedListDS() {
head = tail = null;
currentSize = 0;
}
class Node<E> { //creates Node and has nested constructor
E data;
Node<E> next;
public Node(E data) {
this.data = data;
next = null;
}
}
public void addFirst(E obj) {
Node<E> newNode = new Node(obj);
if (head == null)
head = tail = newNode;
else {
newNode.next = head;
head = newNode;
}
currentSize++;
}
public void addLast(E o) {
Node<E> newNode = new Node(o);
if (head == null)
head = tail = newNode;
else {
tail.next = newNode;
tail = newNode;
}
currentSize++;
}
public E removeFirst() {
if (head == null)
return null;
E tmp = head.data;
head = head.next;
if (head == null) //Checking if the linked list is empty after the execution of the function
tail = null;
currentSize--;
return tmp;
}
public E removeLast() {
Node<E> previous = null;
Node<E> current = head;
if (current == null)
return null;
while (current.next != null) {
previous = current;
current = current.next;
}
if (previous == null) //If the linked list is one element call back to the previous function
return removeFirst();
previous.next = null;
tail = previous;
currentSize--;
return current.data;
}
public E peekFirst() {
if (head == null )
return null;
else
return head.data;
}
public E peekLast() {
if (tail == null)
return null;
else
return tail.data;
}
public E find(E obj) {
if (head == null)
return null;
Node<E> current = head;
while(current != null && ((Comparable<E>)obj).compareTo(current.data) != 0) {
current = current.next;
}
if(current == null) return null;
return current.data;
}
public boolean remove(E obj) {
Node<E> previous = null, current = head;
while (current != null && ((Comparable<E>)obj).compareTo(current.data) != 0) {
previous = current;
current = current.next;
}
if (current == null)
return false;
if (current == head)
removeFirst(); //Use existing function for removing head with remove function
else if (current == tail)
removeLast(); //Use existing function for removing tail with remove function
else {
previous.next = current.next;
currentSize--;
}
return true;
}
public void makeEmpty() {
head = tail = null;
currentSize = 0;
}
public boolean contains(E obj) {
Node<E> current = head;
if(current == null) //Checks if linked list is empty
return false;
while (current != null && ((Comparable<E>)obj).compareTo(current.data) != 0)
current = current.next;
if (current == null)
return false;
return true;
}
public boolean isEmpty() {
if (currentSize==0)
return true;
return false;
}
public boolean isFull() {
return false;
}
public int size() {
return currentSize;
}
public Iterator<E> iterator() {
return new IteratorHelper();
}
class IteratorHelper implements Iterator<E> {
Node<E> iteratorPtr;
public IteratorHelper() {
iteratorPtr = head;
}
public boolean hasNext() {
return iteratorPtr != null;
}
public E next() { //establishing the next function
if (!hasNext())
throw new NoSuchElementException(); //checks if next exists
E temp = iteratorPtr.data;
iteratorPtr = iteratorPtr.next;
return temp;
}
public void remove () {
throw new UnsupportedOperationException();
}
}
}
Explanation / Answer
import java.util.NoSuchElementException;
public class BST<Key extends Comparable<Key>, Value> {
private Node root;
private class Node {
private Key key; // sorted by key
private Value val;
private Node left, right;
private int N; // number of nodes in subtree
public Node(Key key, Value val, int N) {
this.key = key;
this.val = val;
this.N = N;
}
}
public boolean isEmpty() {
return size() == 0;
}
public int size() {
return size(root);
}
private int size(Node x) {
if (x == null) return 0;
else return x.N;
}
public boolean contains(Key key) {
return get(key) != null;
}
public Value get(Key key) {
return get(root, key);
}
private Value get(Node x, Key key) {
if (x == null) return null;
int cmp = key.compareTo(x.key);
if (cmp < 0) return get(x.left, key);
else if (cmp > 0) return get(x.right, key);
else return x.val;
}
public void put(Key key, Value val) {
if (val == null) { delete(key); return; }
root = put(root, key, val);
assert check();
}
private Node put(Node x, Key key, Value val) {
if (x == null) return new Node(key, val, 1);
int cmp = key.compareTo(x.key);
if (cmp < 0) x.left = put(x.left, key, val);
else if (cmp > 0) x.right = put(x.right, key, val);
else x.val = val;
x.N = 1 + size(x.left) + size(x.right);
return x;}
public void deleteMin() {
if (isEmpty()) throw new NoSuchElementException("Symbol table underflow");
root = deleteMin(root);
assert check();
}
private Node deleteMin(Node x) {
if (x.left == null) return x.right;
x.left = deleteMin(x.left);
x.N = size(x.left) + size(x.right) + 1;
return x;
}
public void deleteMax() {
if (isEmpty()) throw new NoSuchElementException("Symbol table underflow");
root = deleteMax(root);
assert check();
}
private Node deleteMax(Node x) {
if (x.right == null) return x.left;
x.right = deleteMax(x.right);
x.N = size(x.left) + size(x.right) + 1;
return x;
}
public void delete(Key key) {
root = delete(root, key);
assert check();
}
private Node delete(Node x, Key key) {
if (x == null) return null;
int cmp = key.compareTo(x.key);
if (cmp < 0) x.left = delete(x.left, key);
else if (cmp > 0) x.right = delete(x.right, key);
else {
if (x.right == null) return x.left;
if (x.left == null) return x.right;
Node t = x;
x = min(t.right);
x.right = deleteMin(t.right);
x.left = t.left;
}
x.N = size(x.left) + size(x.right) + 1;
return x;
}
public Key min() {
if (isEmpty()) return null;
return min(root).key;
}
private Node min(Node x) {
if (x.left == null) return x;
else return min(x.left);
}
public Key max() {
if (isEmpty()) return null;
return max(root).key;
}
private Node max(Node x) {
if (x.right == null) return x;
else return max(x.right);
}
public Key floor(Key key) {
Node x = floor(root, key);
if (x == null) return null;
else return x.key;
}
private Node floor(Node x, Key key) {
if (x == null) return null;
int cmp = key.compareTo(x.key);
if (cmp == 0) return x;
if (cmp < 0) return floor(x.left, key);
Node t = floor(x.right, key);
if (t != null) return t;
else return x;
}
public Key ceiling(Key key) {
Node x = ceiling(root, key);
if (x == null) return null;
else return x.key;
}
private Node ceiling(Node x, Key key) {
if (x == null) return null;
int cmp = key.compareTo(x.key);
if (cmp == 0) return x;
if (cmp < 0) {
Node t = ceiling(x.left, key);
if (t != null) return t;
else return x;
}
return ceiling(x.right, key);
}
public Key select(int k) {
if (k < 0 || k >= size()) return null;
Node x = select(root, k);
return x.key;
}
// Return key of rank k.
private Node select(Node x, int k) {
if (x == null) return null;
int t = size(x.left);
if (t > k) return select(x.left, k);
else if (t < k) return select(x.right, k-t-1);
else return x;
}
public int rank(Key key) {
return rank(key, root);
}
// Number of keys in the subtree less than key.
private int rank(Key key, Node x) {
if (x == null) return 0;
int cmp = key.compareTo(x.key);
if (cmp < 0) return rank(key, x.left);
else if (cmp > 0) return 1 + size(x.left) + rank(key, x.right);
else return size(x.left);
}
public Iterable<Key> keys() {
return keys(min(), max());
}
public Iterable<Key> keys(Key lo, Key hi) {
Queue<Key> queue = new Queue<Key>();
keys(root, queue, lo, hi);
return queue;
}
private void keys(Node x, Queue<Key> queue, Key lo, Key hi) {
if (x == null) return;
int cmplo = lo.compareTo(x.key);
int cmphi = hi.compareTo(x.key);
if (cmplo < 0) keys(x.left, queue, lo, hi);
if (cmplo <= 0 && cmphi >= 0) queue.enqueue(x.key);
if (cmphi > 0) keys(x.right, queue, lo, hi);
}
public int size(Key lo, Key hi) {
if (lo.compareTo(hi) > 0) return 0;
if (contains(hi)) return rank(hi) - rank(lo) + 1;
else return rank(hi) - rank(lo);
}
public int height() { return height(root); }
private int height(Node x) {
if (x == null) return -1;
return 1 + Math.max(height(x.left), height(x.right));
}
public Iterable<Key> levelOrder() {
Queue<Key> keys = new Queue<Key>();
Queue<Node> queue = new Queue<Node>();
queue.enqueue(root);
while (!queue.isEmpty()) {
Node x = queue.dequeue();
if (x == null) continue;
keys.enqueue(x.key);
queue.enqueue(x.left);
queue.enqueue(x.right);
}
return keys;
}
private boolean check() {
if (!isBST()) StdOut.println("Not in symmetric order");
if (!isSizeConsistent()) StdOut.println("Subtree counts not consistent");
if (!isRankConsistent()) StdOut.println("Ranks not consistent");
return isBST() && isSizeConsistent() && isRankConsistent();
}
private boolean isBST() {
return isBST(root, null, null);
}
private boolean isBST(Node x, Key min, Key max) {
if (x == null) return true;
if (min != null && x.key.compareTo(min) <= 0) return false;
if (max != null && x.key.compareTo(max) >= 0) return false;
return isBST(x.left, min, x.key) && isBST(x.right, x.key, max);
}
private boolean isSizeConsistent() { return isSizeConsistent(root); }
private boolean isSizeConsistent(Node x) {
if (x == null) return true;
if (x.N != size(x.left) + size(x.right) + 1) return false;
return isSizeConsistent(x.left) && isSizeConsistent(x.right);
}
private boolean isRankConsistent() {
for (int i = 0; i < size(); i++)
if (i != rank(select(i))) return false;
for (Key key : keys())
if (key.compareTo(select(rank(key))) != 0) return false;
return true;
}
public static void main(String[] args) {
BST<String, Integer> st = new BST<String, Integer>();
for (int i = 0; !StdIn.isEmpty(); i++) {
String key = StdIn.readString();
st.put(key, i);
}
for (String s : st.levelOrder())
StdOut.println(s + " " + st.get(s));
StdOut.println();
for (String s : st.keys())
StdOut.println(s + " " + st.get(s));
}
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.