Question: please complete the size function . I have the LinkedListST class below: public class LinkedListST { private Node first; // the linked list of key-value
please complete the size function. I have the LinkedListST class below:
public class LinkedListST
private Node first; // the linked list of key-value pairs
// a helper linked list data type
private class Node {
private Key key;
private Value val;
private Node next;
public Node(Key key, Value val, Node next) {
this.key = key;
this.val = val;
this.next = next;
}
}
/**
* Initializes an empty symbol table.
*/
public LinkedListST() {
first = null;
}
/**
* get
*
* Returns the value associated with the given key in this symbol table.
*/
public Value get(Key key) {
if (key == null) throw new NullPointerException("argument to get() is null");
for (Node x = first; x != null; x = x.next) {
if (key.equals(x.key))
return x.val;
}
return null;
}
/**
* put
*
* Inserts the specified key-value pair into the symbol table, overwriting the old
* value with the new value if the symbol table already contains the specified key.
* Deletes the specified key (and its associated value) from this symbol table
* if the specified value is null.
*/
public void put(Key key, Value val) {
if (key == null) throw new NullPointerException("first argument to put() is null");
if (val == null) {
delete(key);
return;
}
for (Node x = first; x != null; x = x.next) {
if (key.equals(x.key)) {
x.val = val;
return;
}
}
first = new Node(key, val, first);
}
/**
* delete *
* Removes the specified key and its associated value from this symbol table
* (if the key is in this symbol table).
*/
public void delete(Key key) {
if (key == null) throw new NullPointerException("argument to delete() is null");
first = delete(first, key);
}
/* delete helper function
* delete key in linked list beginning at Node x
* warning: function call stack too large if table is large
*
*/
private Node delete(Node x, Key key) {
if (x == null) return null;
if (key.equals(x.key)) {
return x.next;
}
x.next = delete(x.next, key);
return x;
}
public Iterable
Queue
for ( Node temp = first; temp != null; temp=temp.next) {
theKeys.enqueue(temp.key);
}
return theKeys;
}
/* you should not modify anything above this line */
/**
* size
* size returns the number of key-value pairs in the symbol table.
* it returns 0 if the symbol table is empty.
*/
public int size () {
return -1; // ToDo 1 fix this
}
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