GO LANG combine duplicates using MAP

 package main

import (

"fmt"

)

type Item struct {

Name  string

Value int

}

func combineDuplicates(items []Item) []Item {

// Use a map with string keys (Name)

itemMap := make(map[string]Item)

for _, item := range items {

if existing, found := itemMap[item.Name]; found {

// Merge logic: sum values

existing.Value += item.Value

itemMap[item.Name] = existing

} else {

// Add new unique item

itemMap[item.Name] = item

}

}

// Convert map back to slice

result := make([]Item, 0, len(itemMap))

for _, item := range itemMap {

result = append(result, item)

}

return result

}

func main() {

items := []Item{

{Name: "A", Value: 10},

{Name: "B", Value: 20},

{Name: "A", Value: 15},

{Name: "C", Value: 30},

{Name: "B", Value: 25},

}

combinedItems := combineDuplicates(items)

fmt.Println("Combined Items:")

for _, item := range combinedItems {

fmt.Printf("Name: %s, Value: %d\n", item.Name, item.Value)

}

}

// Reassigning 

Why is reassignment necessary?

• In Go, when you access a struct value from a map like this:

existing := itemMap[item.Name]

You are getting a copy of the struct, not a reference.

If you modify existing.Value, it only affects the local copy, not the original struct in the map.

To actually update the map entry, you need to explicitly reassign the modified struct back:

itemMap[item.Name] = existing