Hashtable_Chaining_ADT

#include <iostream>
#include <list>

int hash(int key, int size) {
	return key % size;
}

template <typename K, typename V>
class Chaining {
private:
	std::list<std::pair<K, V>>* ptr; // Array of lists (buckets)
	int size;

public:
	// Constructor
	Chaining(int s = 10) {
		this->size = s;
		ptr = new std::list<std::pair<K, V>>[this->size];
	}

	// Destructor
	~Chaining() {
		delete[] ptr;
	}

	// Insert a key-value pair
	void insert(K key, V val) {
		std::pair<K, V> p;
		p.first = key;
		p.second = val;
		int idx = hash(key, size);
		ptr[idx].push_back(p);
	}

	// Erase a key-value pair
	void erase(K key) {
		int idx = hash(key, size);
		typename std::list<std::pair<K, V>>::iterator it;
		for (it = ptr[idx].begin(); it != ptr[idx].end(); ++it) {
			if (it->first == key) {
				ptr[idx].erase(it);
				return;
			}
		}
		std::cout << "Key " << key << " not found.\n";
	}

	// Find a value by key
	void find(K key) {
		int idx = hash(key, size);
		typename std::list<std::pair<K, V>>::const_iterator it;
		for (it = ptr[idx].begin(); it != ptr[idx].end(); ++it) {
			if (it->first == key) {
				std::cout << "Key: " << key << ", Value: " << it->second << "\n";
				return;
			}
		}
		std::cout << "Key " << key << " not found.\n";
	}

	// Display the hash table
	void display() const {
		for (int i = 0; i < size; ++i) {
			std::cout << "Bucket " << i << ": ";
		    typename std::list<std::pair<K, V>>::const_iterator it;
			for (it = ptr[i].begin(); it != ptr[i].end(); ++it) {
				std::cout << "(" << it->first << ", " << it->second << ") ";
			}
			std::cout << "\n";
		}
	}
};

int main() {
	Chaining<int, std::string> hashTable(5);

	hashTable.insert(1, "One");
	hashTable.insert(6, "Six");
	hashTable.insert(11, "Eleven");
	hashTable.insert(2, "Two");

	std::cout << "Hash Table Contents:\n";
	hashTable.display();

	std::cout << "\nFinding key 6:\n";
	hashTable.find(6);

	std::cout << "\nErasing key 6:\n";
	hashTable.erase(6);

	std::cout << "\nHash Table After Erase:\n";
	hashTable.display();

	std::cout << "\nFinding key 6 after erase:\n";
	hashTable.find(6);

	return 0;
}