/**
 * Beispiel aus
 *
 * - Algorithmen und Datenstrukturen für Dummies
 *   - von Andreas Gogol-Döring und Thomas Letschert
 *   - Verlag Wiley-VCH; Oktober 2019
 *  - Kapitel 3, Daten und ihre Struktur
 *
 * @author A. Gogol-Döring, Th. Letschert
 */

import Foundation

struct AuD_03_02_FArray {

    static func FArray1(n: Int) -> [Int] {
        var a: [Int] = Array(repeating: 0, count: n+1)
        a[0] = 1
        for i in 1 ... n {
            a[i] = a[i - 1] * i
        }
        return a
    }

    static func FArray2a(n: Int) -> [(Int, Int)] {
        var a: [(Int, Int)] = Array(repeating: (0, 0), count: n+1)
        a[0] = (0, 1)
        for i in 1 ... n {
            a[i] = (i, a[i-1].1 * i)
        }
        return a
    }

    static func FArray2(n: Int) -> [(Int, Int)] {
        var a: [(Int, Int)] = Array(repeating: (0, 0), count: n+1)
        a[0] = (0, 1)
        for i in 1 ... n {
            switch a[i-1] {
            case (_, let x) :
                a[i] = (i, x * i)
            }
        }
        return a
    }

    struct Record {
        var v: Int
        var f: Int
    }

    static func FArray3(n: Int) -> [Record] {
        var a: [Record] = Array(repeating: Record(v: 0, f: 0), count: n+1)
        a[0] = Record(v: 0, f: 1)
        for i in 1 ... n {
            a[i] = Record(v: i, f: a[i-1].f * i)
        }
        return a
    }


    static func FArray3a(n: Int) -> [Record] {
        var a: [Record] = Array(repeating: Record(v: 0, f: 0), count: n+1)
        a[0] = Record(v: 0, f: 1)
        for i in 1 ... n {
            switch (a[i - 1].v, a[i - 1].f) {
            case (let vv, var ff):
                a[i] = Record(v: i, f: i * ff)
            }
        }
        return a
    }

    static func run () {
        print(FArray1(n: 10).map( { v in v.description } ).joined(separator: ","))
        print(FArray2(n: 10)
                .map( { (v: (Int, Int)) in "[\(v.0.description), \(v.1.description)]" } )
                .joined(separator: ",")
        )
        print(FArray2a(n: 10)
                .map( { (v: (Int, Int)) in "[\(v.0.description), \(v.1.description)]" } )
                .joined(separator: ",")
        )
        print(FArray3(n: 10)
                .map( { (v: Record) in "[\(v.v.description), \(v.f.description)]" } )
                .joined(separator: ",")
        )
        print(FArray3(n: 10)
                .map( { (v: Record) in "[\(v.v.description), \(v.f.description)]" } )
                .joined(separator: ",")
        )
    }

}