Wikipedia
The McNuggets version of the coin problem was introduced by Henri Picciotto,
who included it in his algebra textbook co-authored with Anita Wah. Picciotto
thought of the application in the 1980s while dining with his son at
McDonald's, working the problem out on a napkin. A McNugget number is
the total number of McDonald's Chicken McNuggets in any number of boxes.
In the United Kingdom, the original boxes (prior to the introduction of
the Happy Meal-sized nugget boxes) were of 6, 9, and 20 nuggets.

Task

Calculate (from 0 up to a limit of 100) the largest non-McNuggets
number (a number n which cannot be expressed with 6x + 9y + 20z = n
where x, y and z are natural numbers).




func mcnugget(limit) {
    var sv = Array.Empty(limit + 1, false)
    for s in 0^6..limit {
        for n in s^9..limit {
            for t in n^20..limit {
                sv[t] = true
            }
        }
    }
    for i in limit^-1..0 {
        if !sv[i] {
            print("Maximum non-McNuggets number is \(i)")
            return
        }
    }
}
 
mcnugget(100)