Scenario

Develop an algorithm to search and remove data from a hash table using the open addressing technique.

Aim

Implement a hash table using open addressing with linear probing.

Prerequisites

To solve this activity, you have to implement the following methods in the OpenAddrHashTable.java file:

public void put$($K key, V value$)\{$

$//...$

$\}$

private int searchPosition$($K key$)\{$

$//...$

$\}$

public void remove$($K key$)\{$

$//...$

$\}$

public Optional get$($K key$)\{$

$//...$

$\}$

Steps for Completion

Study the pseudocode shown in Snippet $3\mathrm{.}3$ and Snippet $3\mathrm{.}4($shown below$)$ and implement them in Java.

The container class OpenAddrPair will hold your key and value in the hash table.

Have a flag on this container to indicate when an item is deleted.

Use this flag in the put operation to overwrite it if it is deleted. You can use this flag to optimize your get method using the filter method.

insert$($key$,$ value, array$)$

s $=$ length$($array$)$

hashValue $=$ hash$($key$,$ s$)$

i $=0$

while $($i $<$ s and array$[($hashValue $+$ i$)$ mod s$]!=$ null$)$

i $=$ i $+$ l

if $($i $<$ s$)$ array$[($hashValue $+$ i$)$ mod s$]=($key$,$ value$)$

Snippet $3\mathrm{.}3$: Psuedocode for inserting using linear probing

search$($key$,$ array$)$

s $=$ length$($array$)$

hashValue $=$ hash$($key$,$ s$)$

i $=0$

while $($i $<$ s and array$[($hashValue $+$ i$)$ mod s$]!=$ null and array$[($hashValue $+$ i$)$ mod s$].$key $!=$ key$)$

i $=$ i $+1$

keyValue $=$ array$[($hashValue $+$ i$)$ mod s$]$

if $($keyValue $!=$ null && keyValue.key $==$ key$)$ return keyValue.value

else return null

Snippet $3\mathrm{.}4$: Solution pseudocode for searching using linear probing

Grading

Complete each task listed below. Each task contains automated checks which are used to calculate your grade. When you have completed each task by clicking the checkbox, open the task list panel on the left navigation bar and click the "Submit" button.

codes provided:

HashProvider.java

public interface HashProvider $\{$

int hashKey$($K key, int tableSize$)$;

$\}$

HashTable.java

import java.util.Optional;

public interface HashTable $\{$

void put$($K key,V value$)$;

Optional get$($K key$)$;

void remove$($K key$)$;

$\}$

OpenAddrHashTable.java

import java.util.Optional;

public class OpenAddrHashTable implements HashTable $\{$

private final HashProvider hashProvider;

private Pair$[]$ array;

public OpenAddrHashTable$($int capacity, HashProvider hashProvider$)\{$

array $=$ new Pair$[$capacity$]$;

this.hashProvider $=$ hashProvider;

$\}$

public void put$($K key, V value$)\{$

$//$ write your code here

$\}$

private int searchPosition$($K key$)\{$

$//$ write your code here

$\}$

public void remove$($K key$)\{$

$//$ write your code here

$\}$

public Optional get$($K key$)\{$

$//$ write your code here

return Optional.empty$()$;

$\}$

$\}$

OpenAddrPair.java

public class OpenAddrPair $\{$

private final K key;

private final V value;

private boolean deleted;

public OpenAddrPair$($K key, V value$)\{$

this.key $=$ key;

this.value $=$ value;

this.deleted $=$ false;

$\}$

public K getKey$()\{$

return key;

$\}$

public V getValue$()\{$

return value;

$\}$

public boolean isDeleted$()\{$

return deleted;

$\}$

public void setDeleted$($boolean deleted$)\{$

this.deleted $=$ deleted;

$\}$

$\}$

Pair.java

public class Pair $\{$

private final K key;

private final V value;

public Pair$($K key, V value$)\{$

this.key $=$ key;

this.value $=$ value;

$\}$

public K getKey$()\{$

return key;

$\}$

public V getValue$()\{$

return value;

$\}$

$\}$

RemainderHashing.java

public class RemainderHashing implements HashProvider$\{$

public int hashKey$($Integer key, int tableSize$)\{$

return key $\%$ tableSize;

$\}$

public static void main$($String$[]$ args$)\{$

RemainderHashing remainderHashing $=$ new RemainderHashing$()$;

System.out.println$($remainderHashing$.$hashKey$(337481990,1000))$;

System.out.println$($remainderHashing$.$hashKey$(116241990,1000))$;

System.out.println$($remainderHashing$.$hashKey$(983611990,1000))$;

System.out.println$($remainderHashing$.$hashKey$(201031990,1000))$;

System.out.println$($remainderHashing$.$hashKey$(337481990,1447))$;

System.out.println$($remainderHashing$.$hashKey$(116241990,1447))$;

System.out.println$($remainderHashing$.$hashKey$(983611990,1447))$;

System.out.println$($remainderHashing$.$hashKey$(201031990,1447))$;

$\}$

$\}$