Swift 5, Array of custom object, lowest value. Not equal to other values in same array

Question

How do you determine if this array has only a single lowest value?

let scoresExampleOne = [2, 2, 3, 4] // return false

let scoresExampleTwo = [2, 3, 3, 5] // return true 

"scoreValues" are embedded in a custom "Player" object.

I just tried to simplify it for the sake of this question.

Answer 1

All you need is to iterate your collection and keep track of the minimum value and if it repeats or not:

extension Collection {
    func minElement<T: Comparable>(_ predicate: (Element) -> T) -> (element: Element, single: Bool)? {
        guard var minElement = first else { return nil }
        var min = predicate(minElement)
        var single = true
        for element in dropFirst() {
            let value = predicate(element)
            if value > min { continue }
            if value < min {
                minElement = element
                min = value
                single = true
            } else {
                single = false
            }
        }
        return (minElement, single)
    }
    func min<T: Comparable>(_ predicate: (Element) -> T) -> (min: T, single: Bool)? {
        guard let (element, single) = minElement(predicate) else { return nil }
        return (predicate(element), single)
    }
}

---

Playground testing:

struct Player {
    let score: Int
}

---

let players1: [Player] = [.init(score: 2),
                          .init(score: 2),
                          .init(score: 3),
                          .init(score: 4)]
let players2: [Player] = [.init(score: 2),
                          .init(score: 3),
                          .init(score: 3),
                          .init(score: 5)]

---

let scoresExampleOne = players1.min(\.score)          // (min 2, single false)
let scoresExampleTwo = players2.min(\.score)          // (min 2, single true)
let scoresExampleThree = players1.minElement(\.score) // ({score 2}, single false)
let scoresExampleFour = players2.minElement(\.score)  // ({score 2}, single true)