Hashing

In computer science, hashing is a technique used to map data to a fixed-size array called a hash table. It is an efficient way to store and retrieve data based on its key value. Hashing is widely used in various applications, such as indexing and searching.

In simple terms, hashing involves applying a hash function to the input data to generate a unique hash code or hash value. The hash value is then used as an index to store or retrieve the data in the hash table.

In the example code below, we have an array of integers:

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We want to store these integers in a hash table using hashing. To do this, we initialize a hash table of size 100.

In the for loop, we calculate the hash value for each element in the array by taking the modulus of the element with the size of the hash table (100 in this case). The modulus operation ensures that the hash value falls within the range of the hash table.

We then store the element at the calculated index in the hash table. This allows us to quickly retrieve the element when needed.

Finally, we print the elements stored in the hash table.

Hashing provides efficient storage and retrieval of data, making it an essential technique in searching algorithms. It allows for constant-time average-case complexity for searching, inserting, and deleting elements from the hash table.

Hashing is used in various applications, such as database indexing, password storage, and data deduplication. Understanding the principles of hashing is crucial in designing efficient algorithms and solving real-world problems.

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class Main {

  public static void main(String[] args) {

    // replace with your Java logic here

    // Hashing example

    int[] array = {12, 45, 67, 91, 32, 56};

    int size = array.length;

    int[] hashTable = new int[100];

​

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

      int index = array[i] % 100;

      hashTable[index] = array[i];

    }

​

    System.out.println("Elements in the hash table:");

    for (int i = 0; i < 100; i++) {

      if (hashTable[i] != 0) {

        System.out.println(hashTable[i]);

      }

    }

  }

}