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Go

⁠

🔍 Conceptual Difference

Table 11

Table 11

Feature

HashSet

HashMap

Purpose

Store unique keys only

Store key-value pairs

Key Focus

Presence/absence of keys

Association between key and value

Value Storage

Does not store values

Stores values mapped to keys

Use Case

Fast lookup to check membership

Fast lookup, insert, update key-value

There are no rows in this table

⁠

✅ Built-in Go Equivalents

In Go, while there's no native Set type, you can simulate a HashSet using a map[T]struct{} or map[T]bool.

✅ HashSet in Go (Simulated)

CopyEdit

set := make(map[int]struct{}) // or map[int]bool

// Add

set[5] = struct{}{}

// Check

if _, ok := set[5]; ok {

fmt.Println("Exists")

}

// Remove

delete(set, 5)

Here, struct{} is an empty struct that takes 0 bytes. It's commonly used in Go to simulate sets efficiently.

⁠

✅ HashMap in Go

CopyEdit

mp := make(map[int]string)

// Add or Update

mp[1] = "one"

// Get

val, ok := mp[1]

if ok {

fmt.Println("Found:", val)

}

// Remove

delete(mp, 1)

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🧠 When to Use What?

Use a HashSet (i.e., map[T]struct{}) when:

You only care if an item is present or not.

You don't need to store associated values.

Example: Keeping track of visited nodes in a graph.

Use a HashMap (i.e., map[K]V) when:

You need to associate data with each key.

Example: Counting frequencies, caching results.

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👨‍💻 Summary

HashSet = map[int]struct{} → only keys, no values

HashMap = map[int]string → key-value pairs

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