Untitled

/*
 Samarth Kamble
 21142 (F1-Batch)
 Date of start: 21/03/2022
 Date of completion:

 Problem statement:
 Consider telephone book database of N clients. Make use of a hash table
 implementation to quickly look up client‘s telephone number. Make use of two
 collision handling techniques and compare them using number of comparisons
 required to find a set of telephone numbers (use linear probing with replacement and
 without replacement)
 */
#include <iostream>
#define SIZE 123
using namespace std;

class HashEntry {
	long int phoneNumber;
	string name;
public:
	HashEntry() {
		this->name = "";
		this->phoneNumber = -1;
	}
	long int getPhoneNumber() {
		return phoneNumber;
	}
	string getName() {
		return name;
	}
	void setPhoneNumber(long int number) {
		this->phoneNumber = number;
	}
	void setName(string name) {
		this->name = name;
	}
};

class HashTable {
	HashEntry arr[SIZE];
	int entryCount;
public:
	static int multiplyDigits(long int num) {
		int ans = 1;
		while (num) {
			int temp = ((num % 10));
			ans *= temp;
			num /= 10;
		}
		return ans % SIZE;
	}
	static int hash(long int key) {
		int hashCode = multiplyDigits(key);
		return hashCode;
	}
	HashTable() {
		entryCount = 0;
	}
	void makeEntry();
	void insertWithoutReplacement(long, string);
	void insertionWithReplacement(long, string);
	void display() {
		for (int i = 0; i < SIZE; i++) {
			if (arr[i].getPhoneNumber() != -1)
				cout << "At " << "index " << i << ": " << "Phone number- "
						<< arr[i].getPhoneNumber() << " Name- "
						<< arr[i].getName() << endl;
		}
	}
	void search(long int number) {
		int comparisons = 0;
		int hashValue = hash(number);
		int initial = hashValue - 1;
		while (arr[hashValue].getPhoneNumber() != number) {
			if (arr[hashValue].getPhoneNumber() != -1)
				comparisons++;
			hashValue = (hashValue + 1) % SIZE;
			if (hashValue == initial && arr[hashValue].getPhoneNumber() == -1) {
				cout << "\nNot found\n";
				cout << "The comparisons required were " << comparisons << endl;
				return;
			}
		}
		cout << "\nFOUND " << arr[hashValue].getPhoneNumber() << " at index "
				<< hashValue << endl;
		cout << "The comparisons required were " << comparisons << endl;
	}
} *HT = NULL;

void HashTable::makeEntry() {
	long int num;
	string name;
	cout << "\nEnter contact number: ";
	cin >> num;
	cout << "\nEnter your name: ";
	cin.ignore();
	getline(cin, name);
	if (entryCount >= SIZE) {
		cout << "\nHashTable is full\n";
		return;
	}
	int ch;
	cout
			<< "\nEnter 1 to enter without replacement\nEnter 2 to enter with replacement\nEnter: ";
	cin >> ch;
	if (ch == 1)
		insertionWithReplacement(num, name);
	else
		insertionWithReplacement(num, name);
	entryCount++;
}

void HashTable::insertWithoutReplacement(long num, string name) {

	int hashValue = hash(num);
	int position = hashValue;
	while ((arr[position]).getPhoneNumber() != -1) {
		position = (position + 1) % SIZE;
	}
	arr[position].setPhoneNumber(num);
	arr[position].setName(name);
}

void HashTable::insertionWithReplacement(long num, string name) {
	int hashValue = hash(num);
	int position = hashValue;

	if (arr[hashValue].getPhoneNumber() == -1) {
		arr[hashValue].setPhoneNumber(num);
		arr[hashValue].setName(name);
	} else {
		int thisHashValue = hash(arr[position].getPhoneNumber());
		if (thisHashValue == position) {
			while ((arr[position]).getPhoneNumber() != -1) {
				position = (position + 1) % SIZE;
			}
			arr[position].setPhoneNumber(num);
			arr[position].setName(name);
		} else {
			long replacementNum = arr[position].getPhoneNumber();
			string replacementName = arr[position].getName();
			arr[position].setName(name);
			arr[position].setPhoneNumber(num);
			position = (position + 1) % SIZE;

			while ((arr[position]).getPhoneNumber() != -1) {
				position = (position + 1) % SIZE;
			}
			arr[position].setPhoneNumber(replacementNum);
			arr[position].setName(replacementName);
		}
	}
}

int main() {
	HT = new HashTable();
	bool menu = 1;
	int ch;
	while (menu) {
		cout << "\n1.Make an entry\n2.Remove an entry\n3.Display\n4.Search\n";
		cout << "Enter choice: ";
		cin >> ch;

		switch (ch) {
		case 1:
			HT->makeEntry();
			break;
		case 2:

			break;
		case 3:
			HT->display();
			break;
		case 4:
			long int num;
			cout << "\nENter: ";
			cin >> num;
			HT->search(num);
			break;

		case -1:
			menu = 0;
			break;
		default:
			break;
		}
	}
	return 0;
}