Separate Chaining Collision Handling Technique in Hashing | DSA in C++ - Software Development PDF Download

Introduction

Hashing is a popular technique used in computer science to efficiently store and retrieve data. However, collisions can occur when two different keys generate the same hash value. To address this issue, collision handling techniques are employed. One such technique is Separate Chaining, which handles collisions by storing multiple elements in a linked list at each hash index. This article aims to provide a beginner-friendly explanation of the Separate Chaining collision handling technique in hashing, along with code examples and sample problems for better understanding.

What is Separate Chaining?

How Separate Chaining Works?

Here's a step-by-step explanation of how Separate Chaining handles collisions:

• Create an array of linked lists, where each list represents a hash index.
• When inserting an element into the hash table:
  • Compute the hash value of the key.
  • Use the hash value to determine the index in the array.
  • Insert the element at the beginning or end of the linked list at that index.
• When searching for an element:
  • Compute the hash value of the key.
  • Use the hash value to determine the index in the array.
  • Traverse the linked list at that index to find the desired element.

Code Examples

Let's see some code examples in C++ to illustrate Separate Chaining collision handling technique:

#include <iostream>

#include <list>

using namespace std;

class HashTable {

private:

    int capacity;

    list<int>* table;

public:

    HashTable(int capacity) {

        this->capacity = capacity;

        table = new list<int>[capacity];

    }

    void insert(int key) {

        int index = key % capacity;

        table[index].push_back(key);

    }

    bool search(int key) {

        int index = key % capacity;

        for (auto it = table[index].begin(); it != table[index].end(); ++it) {

            if (*it == key) {

                return true;

            }

        }

        return false;

    }

};

int main() {

    HashTable ht(10);

    ht.insert(5);

    ht.insert(15);

    ht.insert(25);

    cout << "Search 15: " << (ht.search(15) ? "Found" : "Not Found") << endl;

    cout << "Search 20: " << (ht.search(20) ? "Found" : "Not Found") << endl;

    return 0;

}

Output:

Search 15: Found

Search 20: Not Found

Explanation:

• In the code example, we create a HashTable class that implements Separate Chaining.
• The 'insert' function calculates the hash value of the key using the modulo operation and inserts the key at the corresponding index.
• The 'search' function calculates the hash value of the key and traverses the linked list at that index to find the key.

Sample Problems with Solutions

Problem 1: Implement a hash table using Separate Chaining that supports the following operations: 'insert(key), search(key), and remove(key)'.

// TODO: Provide the solution code for the problem.

Problem 2: Find the first non-repeating element in an array using Separate Chaining.

// TODO: Provide the solution code for the problem.

Conclusion

Separate Chaining is a collision handling technique in hashing that uses linked lists to store multiple elements at the same hash index. It provides an efficient way to handle collisions and ensures a good distribution of data. By understanding the concept and exploring code examples, you can now leverage Separate Chaining in your own programs when implementing hash tables.