Question

Implement an eager delete() method for linear probing hash table. The eager delete will delete the pair from the hash table, not just set the value to null.
*Algorithhms*

In Java Language Please

I want to add the delete method to this hash table code.

public class Linear ProbingHashST<Key, Value> private int M = 30001; private Value [] vals = (Value[]) new Object[M]: private Key [] keys = (Key []) new Object[M]: array doubling and halving code omitted private int hash (key key) { / as before */ } private void put(key key, Value val) { / next slide public Value get(key key) for (int i = hash (key): keys [1] != null: 1 = (1+1) * NO if (key.equals(keys[i])) return vals[1]: return null;

Answer 1

Here is the Solution :

I have added boolean remove(final long key) to delete the item & Created One Test class UsageHash to test the functionality. I have explained all important lines by using Java comments.

class HashTableEx {
final int SIZE = 300001; // size of the table
long[] a = new long[SIZE]; int[] ex = new int[SIZE];
// adds new key
boolean add(final long key) {
int i = h(key), j = 1;
for (; ex[i] != 0; i = (i + 1) % SIZE, j++)
if (a[i] == key)
return false;
ex[i] = j;
a[i] = key;
return true;
}

// returns true, if key is contained in the table
boolean contains(final long key) {
for (int i = h(key); ex[i] != 0; i = (i + 1) % SIZE)
if (a[i] == key)
return true;
return false;
}

// removes key from the table
boolean remove(final long key) {
for (int i = h(key); ex[i] != 0; i = (i + 1) % SIZE)
if (a[i] == key) {
ex[i] = 0;
compress(i);
return true;
}
return false;
}

// compresses lists
void compress(int free) {
int i = (free + 1) % SIZE, off = 1;
for (; ex[i] != 0; i = (i + 1) % SIZE, off++)
if (ex[i] > off) {
// move current element
a[free] = a[i];
ex[free] = ex[i] - off;
// mark current slot as free
ex[i] = 0;
off = 0;
free = i;
}
}

int h(final long key) {
return (int) Math.abs(key % SIZE);
}
}
  
public class UsageHash
{
public static void main(String[] args)
{
//Creating instance of HashTableEX
HashTableEx objh=new HashTableEx();
objh.add(12);
objh.add(13);
//Checking if 12 Exist !!! before Removing
System.out.println("Output Before Deletion :"
+objh.contains(12));
//Removing 12 From HashTableEx
objh.remove(12);
//Checking Hash Table after Removing 12
System.out.println("Output After Deletion :"
+objh.contains(12));
  
}
}