**What Is Index Mapping in Data Structure?**

Data structures play a crucial role in organizing and manipulating data efficiently. One such data structure is Index Mapping, also known as Hashing.

Index Mapping is a technique used to store and retrieve data elements based on their unique keys. It provides an efficient way to search, insert, and delete elements from a collection of data.

## Understanding Index Mapping

At its core, Index Mapping involves mapping each data element to a unique index in an array. This mapping is done using a hash function, which takes the key as input and returns the corresponding index in the array. The array acts as a container for storing the actual data elements.

__Example:__

Let’s consider an example where we have a collection of students with their respective roll numbers. We can use Index Mapping to store these students’ details in an array for quick retrieval based on their roll numbers.

We can define our hash function as:

`hash(key) = key % array_size`

In this case, the hash function takes the roll number as input and returns the remainder when divided by the size of the array. This ensures that each student is mapped to a unique index within the array.

### The Process

The process of storing and retrieving data using Index Mapping involves three main steps:

**Initialization:**Create an empty array with a fixed size to hold the data elements.**Insertion:**For each data element, calculate its hash value using the hash function. Place the element at the corresponding index in the array.**Retrieval:**To retrieve a data element, calculate its hash value using the same hash function. Access the element at the corresponding index in the array.

### Advantages of Index Mapping

Index Mapping offers several advantages:

**Fast access:**Retrieving data elements based on their keys is fast since it involves a direct mapping to array indexes.**Space efficiency:**Index Mapping typically uses less memory compared to other data structures like linked lists or trees.**Collision handling:**In case of a hash collision (when two elements have the same hash value), various collision resolution techniques can be applied to ensure efficient storage and retrieval.

## In Conclusion

Index Mapping, also known as Hashing, is a powerful technique used in data structures for efficient storage and retrieval of data elements based on their unique keys. By mapping each element to a unique index in an array using a hash function, Index Mapping provides fast access and space efficiency. It is widely used in various applications that require quick searching and retrieval of data.

If you are interested in learning more about Index Mapping and other data structures, continue exploring HTML tutorials!