Rugby World Cup 2019 Sweepstakes

Sweepstakes.swift

import Foundation

class Person {
    let name: String
    private var teams = [Team]()
    
    public var sortedTeams: [Team] {
        return teams.sorted(by: { $0.rank < $1.rank })
    }
    
    public var highestTeamRank: Int? {
        return teams.map { $0.rank }.max()
    }
    
    public var lowestTeamRank: Int? {
        return teams.map { $0.rank }.min()
    }
    
    init(name: String) {
        self.name = name
    }
    
    public func add(_ team: Team) {
        teams.append(team)
    }
}

class Team {
    let name: String
    let rank: Int
    
    init(name: String, rank: Int) {
        self.name = name
        self.rank = rank
    }
}

final class Sweepstakes {
    static let sharedInstance = Sweepstakes()
    private init() {}
    
    private var people = [Person]()
    private var teams = [Team]()
    
    func set(people: [Person]) {
        self.people = people
    }
    
    func setPeopleByNames(_ names: [String]) {
        self.people = names.map { Person(name: $0) }
    }
    
    func setPeopleByNames(_ names: String...) {
        self.people = names.map { Person(name: $0) }
    }
    
    /// Default value WRC-2019 teams. Rankings accurate as of 19 August 2019.
    func setTeams(_ teams: [Team] = [Team(name: "Ireland", rank: 3), Team(name: "Scotland", rank: 8), Team(name: "Japan", rank: 9), Team(name: "Russia", rank: 20), Team(name:"Samoa", rank: 16), Team(name: "New Zealand", rank: 2), Team(name: "South Africa", rank: 4), Team(name: "Italy", rank: 13), Team(name: "Namibia", rank: 23), Team(name: "Canada", rank: 21), Team(name: "England", rank: 5), Team(name: "France", rank: 7), Team(name: "Argentina", rank: 11), Team(name: "United States", rank: 14), Team(name: "Tonga", rank: 15), Team(name: "Australia", rank: 6), Team(name: "Wales", rank: 1), Team(name: "Georgia", rank: 12), Team(name: "Fiji", rank: 10), Team(name: "Uruguay", rank: 19)] ) {
        self.teams = teams
    }
    
    func performSweepStakesAssignment(people: [String], teams: [String]) {
        assert(!people.isEmpty && !teams.isEmpty && people.count <= teams.count, "Illegal combination of people/teams - both must be non-empty and #people <= #teams")
        
        var shuffledTeams = teams.shuffled()
        
        for person in people.shuffled() {
            guard let randomTeam = shuffledTeams.popLast() else {
                print("SWEEPSTAKES - No more teams left to assign for \(person)")
                return
            }
            print("SWEEPSTAKES - \(person) --> \(randomTeam)")
            shuffledTeams.shuffle()
        }
        
        print("SWEEPSTAKES - ASSIGNMENTS DONE, LEFTOVER TEAMS: \(shuffledTeams)")
        
    }
    
    func performAssignment() {
        assert(!people.isEmpty && !teams.isEmpty && people.count <= teams.count, "Illegal combination of people/teams - both must be non-empty and #people <= #teams")
        
        print("SWEEPSTAKES - First round of assignments\n")
        
        var shuffledTeams = teams.shuffled()
        
        for person in people.shuffled() {
            guard let randomTeam = shuffledTeams.popLast() else {
                print("SWEEPSTAKES - No more teams left to assign for \(person)")
                return
            }
            print("SWEEPSTAKES - \(person.name) --> \(randomTeam.name) (#\(randomTeam.rank))")
            person.add(randomTeam)
            shuffledTeams.shuffle()
        }
        
        if !shuffledTeams.isEmpty {
            print("\nSWEEPSTAKES - Initial assignments done, leftover teams: \(shuffledTeams.compactMap { $0.name })")
            assignLeftOver(shuffledTeams)
            prettyPrintAssignments()
        } else {
            print("\nSWEEPSTAKES - Assignments complete, no leftover teams")
        }
    }
    
    /// Assign leftover teams to people according to rank (give to those with the worst "best" rank first)
    private func assignLeftOver(_ teams: [Team]) {
        print("\nSWEEPSTAKES - Begin clearing assignments")
        for team in teams.shuffled() {
            print("SWEEPSTAKES - Assigned \(team.name) (#\(team.rank)) to \(people.sorted(by: { $0.lowestTeamRank ?? Int.max < $1.lowestTeamRank ?? Int.max}).last?.name ?? "N/A")")
            self.people.sorted(by: { $0.lowestTeamRank ?? Int.max < $1.lowestTeamRank ?? Int.max}).last?.add(team)
        }
    }
    
    public func prettyPrintAssignments() {
        print("\nSWEEPSTAKES - Assignments")
        people.forEach {
            print("SWEEPSTAKES - \($0.name) --> teams: \($0.sortedTeams.compactMap { $0.name + " (#\($0.rank))" })")
        }
    }
}

Example usage (you can copy and paste the code into a new playground):

Sweepstakes.sharedInstance.setPeopleByNames("Adam", "Betty", "Charlie", "Danny", "Ellen", "Frank", "Gary")
Sweepstakes.sharedInstance.setTeams()
Sweepstakes.sharedInstance.performAssignment()

Example output:

SWEEPSTAKES - First round of assignments

SWEEPSTAKES - Frank --> Italy (#13)
SWEEPSTAKES - Danny --> Scotland (#8)
SWEEPSTAKES - Gary --> Wales (#1)
SWEEPSTAKES - Adam --> New Zealand (#2)
SWEEPSTAKES - Betty --> Canada (#21)
SWEEPSTAKES - Ellen --> Japan (#9)
SWEEPSTAKES - Charlie --> Australia (#6)

SWEEPSTAKES - Initial assignments done, leftover teams: ["Argentina", "Russia", "South Africa", "Georgia", "Namibia", "Tonga", "United States", "Uruguay", "Fiji", "Samoa", "England", "France", "Ireland"]

SWEEPSTAKES - Begin clearing assignments
SWEEPSTAKES - Assigned Uruguay (#19) to Betty
SWEEPSTAKES - Assigned France (#7) to Betty
SWEEPSTAKES - Assigned Fiji (#10) to Frank
SWEEPSTAKES - Assigned Samoa (#16) to Frank
SWEEPSTAKES - Assigned South Africa (#4) to Frank
SWEEPSTAKES - Assigned Argentina (#11) to Ellen
SWEEPSTAKES - Assigned Ireland (#3) to Ellen
SWEEPSTAKES - Assigned England (#5) to Danny
SWEEPSTAKES - Assigned Tonga (#15) to Betty
SWEEPSTAKES - Assigned United States (#14) to Betty
SWEEPSTAKES - Assigned Russia (#20) to Betty
SWEEPSTAKES - Assigned Namibia (#23) to Betty
SWEEPSTAKES - Assigned Georgia (#12) to Betty

SWEEPSTAKES - Assignments
SWEEPSTAKES - Adam --> teams: ["New Zealand (#2)"]
SWEEPSTAKES - Betty --> teams: ["France (#7)", "Georgia (#12)", "United States (#14)", "Tonga (#15)", "Uruguay (#19)", "Russia (#20)", "Canada (#21)", "Namibia (#23)"]
SWEEPSTAKES - Charlie --> teams: ["Australia (#6)"]
SWEEPSTAKES - Danny --> teams: ["England (#5)", "Scotland (#8)"]
SWEEPSTAKES - Ellen --> teams: ["Ireland (#3)", "Japan (#9)", "Argentina (#11)"]
SWEEPSTAKES - Frank --> teams: ["South Africa (#4)", "Fiji (#10)", "Italy (#13)", "Samoa (#16)"]
SWEEPSTAKES - Gary --> teams: ["Wales (#1)"]