Question

我有一个2D数组：

    override func viewDidLoad() {
        super.viewDidLoad()
        self.navigationItem.title = "Vyhodnotenie testu"
        self.showAlert()

    }


    func showAlert() {
        func callback(){}
        if numberOfPoints > 49 {
            let customIcon = UIImage(named: "smile")
            let alertview = JSSAlertView().show(self, title: "Gratulujeme! Uspeli ste.", text: "Dokončili ste test s počtom bodov \(numberOfPoints + 1) z \(maximumNumberOfPoints)!", buttonText: "OK!", color: UIColorFromHex(0x22c411, alpha: 1), iconImage: customIcon)
            alertview.setTextTheme(.Light)
            alertview.addAction(myCancelCallback)
            self.navigationController?.navigationBar.alpha = 0.7
        } else {
            let customIcon = UIImage(named: "sad")
            let alertview = JSSAlertView().show(self, title: "Ľutujeme! Neuspeli ste.", text: "Dokončili ste test s počtom bodov \(numberOfPoints + 1) z \(maximumNumberOfPoints)!", buttonText: "OK!", color: UIColorFromHex(0xd20606, alpha: 1), iconImage: customIcon)
            alertview.addAction(myCancelCallback)
            alertview.setTextTheme(.Light)
            self.navigationController?.navigationBar.alpha = 0.7
        }

    }

    func myCancelCallback() {
        self.navigationController?.navigationBar.alpha = 1.0
        self.interstitialPresentationPolicy = ADInterstitialPresentationPolicy.Automatic
    }


    func interstitialAdWillLoad(interstitialAd: ADInterstitialAd!) {

    }

    func interstitialAdDidLoad(interstitialAd: ADInterstitialAd!) {
        interstitialAdView = UIView()
        interstitialAdView.frame = self.view.bounds
        view.addSubview(interstitialAdView)

        interstitialAd.presentInView(interstitialAdView)
        UIViewController.prepareInterstitialAds()
    }

    func interstitialAdActionDidFinish(var interstitialAd: ADInterstitialAd!) {
        interstitialAd = nil
        interstitialAdView.removeFromSuperview()
    }

    func interstitialAdActionShouldBegin(interstitialAd: ADInterstitialAd!, willLeaveApplication willLeave: Bool) -> Bool {
        return true
    }

    func interstitialAd(interstitialAd: ADInterstitialAd!, didFailWithError error: NSError!) {

    }

    func interstitialAdDidUnload(var interstitialAd: ADInterstitialAd!) {
        interstitialAd = nil
        interstitialAdView.removeFromSuperview()
    }

子阵列的第一个元素是用户名，第二个元素是得分。

我需要返回最高分的用户名。例如，这里它将返回[["user1", 20], ["user2", 30], ["user3", 10]]。

一个用户的分数较高，或者他们都有相同的分数（在这种情况下，它应该返回"user2"）。

我知道如何通过一堆迭代和多行代码来实现这一点，但我正在努力寻找“最佳实践方式”。

你会建议什么？

Answer 1

查看max_by

users = [["user1", 20], ["user2", 30], ["user3", 10]]

users.max_by{ |user, weight| weight }
#=> ["user2", 30]

# shorthand
users.max_by(&:last)
#=> ["user2", 30]

users.max_by(&:last).first
#=> "user2"

值得一提的是，如果你有多个最大值，它将只返回第一个。

Answer 2

给定示例的简单解决方案：

a = [["user1", 20], ["user2", 30], ["user3", 10]]
h = Hash[a].invert
h[h.keys.max]
#=> "user2"

在一般情况下，如果出现相同的最大数字，以下解决方案将返回所有共享相同最大值的用户（由Nigel执行w /反转功能，请参阅Swapping keys and values in a hash）：

class Hash
  def safe_invert
    self.each_with_object( {} ) { |(key, value), out| ( out[value] ||= [] ) << key }
  end
end

a = [["user1", 20], ["user2", 30], ["user3", 10], ["user4", 30]]
h = Hash[a].safe_invert
h[h.keys.max]
#=> ["user2", "user4"]

返回2D Array的最大值

2 个答案: