/**
 * Beispiel aus
 *
 * - Algorithmen und Datenstrukturen für Dummies
 *   - von Andreas Gogol-Döring und Thomas Letschert
 *   - Verlag Wiley-VCH; Oktober 2019
 *  - Kapitel 11, Probleme totschlagen
 *
 * @author A. Gogol-Döring, Th. Letschert
 */

import Foundation

struct AuD_11_02_TwoQueensArrangement {

    // Erzeugt alle möglichen Positionen in einen 2x2 Feld
    static func TwoQPositionsV1() -> [(Int, Int)] {
        var result: [(Int, Int)] = []
        for i in 0 ... 1 {
            for j in 0...1 {
                result = result + [(i, j)]
            }
        }
        return result
    }

    // Erzeugt alle möglichen Positionen in einen 2x2 Feld
    // funktionale Variante
    static func TwoQPositionsV2() -> [(Int, Int)] {
        (0...1).flatMap({ (i) in (0...1).map({ (j) in (i, j) }) })
    }

    static let TwoQPositions = TwoQPositionsV2

    // Erzeugt alle möglichen Paare von Positionen
    static func TwoQSearchSpaceV1() -> [((Int, Int), (Int, Int))] {
        var result: [((Int, Int), (Int, Int))] = []
        for p_0 in TwoQPositions() {
            for p_1 in TwoQPositions() {
                result = result + [(p_0, p_1)]
            }
        }
        return result
    }

    // Erzeugt Paare von Positionen ohne symetrische Paare
    static func TwoQSearchSpaceV2() -> [((Int, Int), (Int, Int))] {
        var result: [((Int, Int),(Int, Int))] = []
        for p_0 in TwoQPositions() {
            for p_1 in TwoQPositions() {
                if ((p_0 != p_1)
                    && (result.filter( { (pa, pb) in
                        switch (pa, pb) {
                        case ((let x, let y), (let u, let v)) :
                            return p_1.0 == x && p_1.1 == y && p_0.0 == u && p_0.1 == v
                        }
                    } ).count == 0) ) {
                    result = result + [(p_0, p_1)]
                }
            }
        }
        return result
    }

    static func run() {
        print(TwoQSearchSpaceV1())
        print()
        print(TwoQSearchSpaceV2())
    }

}