Question

Please answer this problem in C++, Thank you!

Read and study the sample program: "hashing with chaining using singly linked lists", as well as "hashing with chaining using doubly linked lists". Notice this program is complete except it doesn't include the remove function.

Write the remove function and test it with the rest of the program including the given main program. Upload your C++ source file.

---Here is the referenced program: "hashing with chaining using singly linked lists". Below this program, you will find the referenced, and incomplete program: "hashing with chaining using singly linked lists.

// Program to implement hashing with chaining
#include<iostream>
#include <list>
using namespace std;
  
class Hash
{
int BUCKET; // No. of buckets
  
// Pointer to an array containing buckets
list<int> *table;
public:
Hash(int V); // Constructor
  
// inserts a key into hash table
void insertItem(int x);
  
// deletes a key from hash table
void deleteItem(int key);
  
// hash function to map values to key
int hashFunction(int x) {
return (x % BUCKET);
}
  
void displayHash();
};
  
Hash::Hash(int b)
{
this->BUCKET = b;
table = new list<int>[BUCKET];
}
  
void Hash::insertItem(int key)
{
int index = hashFunction(key);
table[index].push_back(key);
}
  
void Hash::deleteItem(int key)
{
// get the hash index of key
int index = hashFunction(key);
  
// find the key in (inex)th list
list <int> :: iterator i;
for (i = table[index].begin();
i != table[index].end(); i++) {
if (*i == key)
break;
}
  
// if key is found in hash table, remove it
if (i != table[index].end())
table[index].erase(i);
}
  
// function to display hash table
void Hash::displayHash() {
for (int i = 0; i < BUCKET; i++) {
cout << i;
for (auto x : table[i])
cout << " --> " << x;
cout << endl;
}
}
  
// Driver program
int main()
{
// array that contains keys to be mapped
int a[] = {15, 11, 27, 8, 12};
int n = sizeof(a)/sizeof(a[0]);
  
// insert the keys into the hash table
Hash h(7); // 7 is count of buckets in
// hash table
for (int i = 0; i < n; i++)
h.insertItem(a[i]);
  
// delete 12 from hash table
h.deleteItem(12);
  
// display the Hash table
h.displayHash();
return 0;
}

---Below is the referenced "hashing with chaining using doubly linked list" program. As stated in the instructions above, please write the remove function for this program and test it with the rest of the program including the given main program

#include <iostream>

using namespace std;

  const int tablesize = 25;

  

// declaration of node

struct hash_node {

    int val, key;

    hash_node* next;

    hash_node* prev;

};

  

// hashmap's declaration

class HashMap {

public:

    hash_node **hashtable, **top;

  

    // constructor

    HashMap()

    {

        // create a empty hashtable

        hashtable = new hash_node*[tablesize];

        top = new hash_node*[tablesize];

        for (int i = 0; i < tablesize; i++) {

            hashtable[i] = NULL;

            top[i] = NULL;

        }

    }

  

    // destructor

    ~HashMap()

    {

        delete[] hashtable;

    }

  

    // hash function definition

    int HashFunc(int key)

    {

        return key % tablesize;

    }

  

    // searching method

    void find(int key)

    {

        // Applying hashFunc to find

        // index for given key

        int hash_val = HashFunc(key);

        bool flag = false;

        hash_node* entry = hashtable[hash_val];

  

        // if hashtable at that index has some

        // values stored

        if (entry != NULL) {

            while (entry != NULL) {

                if (entry->key == key) {

                    flag = true;

                }

                if (flag) {

                    cout << "Element found at key "

                         << key << ": ";

                    cout << entry->val << endl;

                }

                entry = entry->next;

            }

        }

        if (!flag)

            cout << "No Element found at key "

                 << key << endl;

    }

  

//Removing an element to be done by the student.

  

    // inserting method

    void add(int key, int value)

    {

        // Applying hashFunc to find

        // index for given key

        int hash_val = HashFunc(key);

        hash_node* entry = hashtable[hash_val];

  

        // if key has no value stored

        if (entry == NULL) {

            // creating new node

            entry = new hash_node;

            entry->val = value;

            entry->key = key;

            entry->next = NULL;

            entry->prev = NULL;

            hashtable[hash_val] = entry;

            top[hash_val] = entry;

        }

  

        // if some values are present

        else {

            // traversing till the end of

            // the list

            while (entry != NULL)

                entry = entry->next;

  

            // creating the new node

            entry = new hash_node;

            entry->val = value;

            entry->key = key;

            entry->next = NULL;

            entry->prev = top[hash_val];

            top[hash_val]->next = entry;

            top[hash_val] = entry;

        }

        cout << "Value " << value << " was successfully"

                " added at key " << key << endl;

    }

};

  

// Driver Code

int main()

{

    HashMap hash;

    hash.add(4, 5);

    hash.find(4);

    hash.remove(4);

    return 0;

}

Answer 1

Here is the required code for the problem

#include <iostream>

using namespace std;

const int tablesize = 25;

  

// declaration of node

struct hash_node {

int val, key;

hash_node* next;

hash_node* prev;

};

  

// hashmap's declaration

class HashMap {

public:

hash_node **hashtable, **top;

  

// constructor

HashMap()

{

// create a empty hashtable

hashtable = new hash_node*[tablesize];

top = new hash_node*[tablesize];

for (int i = 0; i < tablesize; i++) {

hashtable[i] = NULL;

top[i] = NULL;

}

}

  

// destructor

~HashMap()

{

delete[] hashtable;

}

  

// hash function definition

int HashFunc(int key)

{

return key % tablesize;

}

  

// searching method

void find(int key)

{

// Applying hashFunc to find

// index for given key

int hash_val = HashFunc(key);

bool flag = false;

hash_node* entry = hashtable[hash_val];

  

// if hashtable at that index has some

// values stored

if (entry != NULL) {

while (entry != NULL) {

if (entry->key == key) {

flag = true;

}

if (flag) {

cout << "Element found at key "

<< key << ": ";

cout << entry->val << endl;

}

entry = entry->next;

}

}

if (!flag)

cout << "No Element found at key "

<< key << endl;

}

  

//Removing an element to be done by the student.
void remove(int key)
{
// Applying hashFunc to find

// index for given key

int hash_val = HashFunc(key);

hash_node* entry = hashtable[hash_val];

if (entry->key != key || entry == NULL) {

cout << "no element at this key"

<< key << endl;

return;

}
  
// if any value is present at that key &

// traversing the list and removing all values

while (entry != NULL) {

if (entry->next == NULL) {

if (entry->prev == NULL) {

hashtable[hash_val] = NULL;

top[hash_val] = NULL;

delete entry;

break;

}
else
{
top[hash_val] = entry->prev;

top[hash_val]->next = NULL;

delete entry;

entry = top[hash_val];
}

}

entry = entry->next;

}
cout << "Element was successfully removed at the key "
<< key << endl;
}

  

// inserting method

void add(int key, int value)

{

// Applying hashFunc to find

// index for given key

int hash_val = HashFunc(key);

hash_node* entry = hashtable[hash_val];

  

// if key has no value stored

if (entry == NULL) {

// creating new node

entry = new hash_node;

entry->val = value;

entry->key = key;

entry->next = NULL;

entry->prev = NULL;

hashtable[hash_val] = entry;

top[hash_val] = entry;

}

  

// if some values are present

else {

// traversing till the end of

// the list

while (entry != NULL)

entry = entry->next;

  

// creating the new node

entry = new hash_node;

entry->val = value;

entry->key = key;

entry->next = NULL;

entry->prev = top[hash_val];

top[hash_val]->next = entry;

top[hash_val] = entry;

}

cout << "Value " << value << " was successfully"

" added at key " << key << endl;

}

};

  

// Driver Code

int main()

{

HashMap hash;

hash.add(4, 5);

hash.find(4);

hash.remove(4);

return 0;

}

here is the ss of the output

Value 5 was successfully added at key 4 Element woundsuctesstuiiy 'removed at the key 4 Element was successfully removed at the key 4 PS D:\mingw-w64\1686-8.1.0-posix-dwarf-rt-v6_revo、mi naw 32\bin>

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