# Inventory Update Problem in Swift

Leonardo Maia Pugliese

Published on Apr 30, 2020

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Hey guys Leo here,

Today we'll continue the series Algorithms, the Final Frontier. Always remember folks, this is ONE of many possible solution for the problem. The challenge is here: The Challenge

Let's go!

The problem: Compare and update the inventory stored in a 2D array against a second 2D array of a fresh delivery. E.G. updateInventory([[21, "Bowling Ball"], [2, "Dirty Sock"], [1, "Hair Pin"], [5, "Microphone"]], [[2, "Hair Pin"], [3, "Half-Eaten Apple"], [67, "Bowling Ball"], [7, "Toothpaste"]]) should return an array with a length of 6.

Solution:

I divide this problem in two parts:

1. Create a compiled inventory
2. Sort the compiled inventory

For the first part you can just create a dictionary for that like:

``````var a1 = [[2,"cafe"],[8,"water"],[2,"bola"],[2,"futebolball"],[2,"solarium"],[2,"pool"]]
var a2 = [[8,"cafe"],[3,"water"],[2,"futebolball"],[2,"solarium"],[2,"pool"]]

var dict : [String:Int] = [:]

a1.append(contentsOf: a2)

for row in a1 {
let itemNumber = row[0] as! Int
let itemName = row[1] as! String
if dict[itemName] != nil {
dict[itemName] = dict[itemName]! + itemNumber
} else {
dict[itemName] = itemNumber
}
}
``````

and for the second part just a little FP here :

``````print(dict.lazy.sorted { a1, a2 -> Bool in
a1.key < a2.key
}.map { itemName,value -> [Any] in
[value,itemName]
})
``````

That's all folks!

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