/**
 * Beispiel aus
 *
 * - Algorithmen und Datenstrukturen für Dummies
 *   - von Andreas Gogol-Döring und Thomas Letschert
 *   - Verlag Wiley-VCH; Oktober 2019
 *  - Kapitel 6, Graphen: Jeder mit jedem
 *
 * @author A. Gogol-Döring, Th. Letschert
 */

import Foundation

struct AuD_06_04_VampInfluencer {

    static let V = ["Vlad", "Brunhilde", "Olga", "Rudiger", "Hildegard", "Anna"]
    static let E = [
        ("Vlad", ["Olga", "Hildegard"]), 
        ("Brunhilde", ["Rudiger"]), 
        ("Olga", ["Hildegard", "Anna"]), 
        ("Rudiger", []), 
        ("Hildegard", []), 
        ("Anna", ["Rudiger", "Hildegard"])
    ]

    static func MaxReachable(E: [ (String, [String]) ] ) -> String {

        func R(v: String) -> [String] {

            var M: [String] = []

            func Reach(E: [(String, [String])], v: String) -> [String] {
                M = [v] + M
                var result = [v]
                for (x, ww) in E {
                    if (x == v) {
                        for w in ww {
                            if (!M.contains(w)) {
                                result = result + Reach(E: E, v: w)
                            }
                        }
                        return result
                    }
                }
                return []
            }
            return Reach(E: E, v: v)
        }

        return E . map ( { (p: (String, [String]) ) in p.0 } ) // vertices
                . map( { (s: String) -> [String] in R(v: s) } )   // R of vertices
                . max( by: { (a:[String], b:[String]) -> Bool in a.count < b.count } )![0]
    }

    static func run() {
        print(MaxReachable(E:E))
    }
}