How to Represent and Use Composite Keys in Go Hash Tables?

Creating Composite Keys for Hash Tables in Go

In Go, hash tables are valuable data structures for efficiently storing and retrieving data based on unique keys. However, when dealing with multiple values that combine to form a composite key, determining how to represent and use this key within a hash table can be a challenge.

Representing Composite Keys

To represent a composite key, one effective approach is to define a custom data structure known as a "Key" struct. This struct encapsulates the individual values that make up the key:

type Key struct {
    X, Y int
}

By using a struct, you can combine multiple values into a single key, making it easy to compare and identify different keys within the hash table.

Using the Custom Key Type

Once the custom Key struct is defined, you can create a hash table with this key type:

m := map[Key]int{}

This hash table uses the Key struct as the key type and stores integer values associated with each key.

Example Usage

Let's consider the example of storing computed values of pow(x, y) in the hash table, where x and y are integers. Using the Key struct, we can generate a key for each pair (x, y):

m := map[Key]int{}
m[Key{2, 2}] = 4
m[Key{2, 3}] = 8

Now, to retrieve the value for a specific pair, you can simply use the same Key struct:

fmt.Println("2^2 = ", m[Key{2, 2}])
fmt.Println("2^3 = ", m[Key{2, 3}])

This approach provides a flexible and efficient way to store and retrieve data using composite keys in a hash table.

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