This gist is the practice of knapsack problem. The solution without optimization by using memoization.

Knapsack_Problem.swift

import Foundation

func knapsack(_ weights: Array<Int>,_ values: Array<Int>,_ index: Int,_ remainingWeight: Int) -> Int {
    
    if (index < 0) { return 0 }
    
    var choosedValue: Int = 0
    if (remainingWeight >= weights[index]) {
        // Choose
        choosedValue = values[index] + knapsack(weights, values, index - 1, remainingWeight - weights[index])
    }
    
    // Not choose
    let notChoosedValue = knapsack(weights, values, index - 1, remainingWeight)
    
    return max(choosedValue, notChoosedValue)
}

let weights = [2, 5, 3]
let values = [10, 1, 2]
let weightLimit = 2

let mostValue = knapsack(weights, values, weights.count - 1, weightLimit)

print("[Knapsack] The most value can be carried is \(mostValue)")