用有限的硬币在C＃中进行硬币找零 [英] Coin change in C# with limited coins

问题描述

我构建了下面的硬币找零（C＃），它非常有效：

I built the following coin change (C#) that works perfectly:

class Program
    {

        static int amount = 0;

        static void Main(string[] args)
        {

            EnterAmount();

            int[] coins = new int[] { 500, 100, 50, 20, 10, 5, 2, 1 };

            int Results = 0;

            for (int i = 0; i < coins.Length; i++)
            {
                    Results = amount / coins[i];
                    Console.WriteLine(Results + " x " + coins[i]);
                    amount -= Results * coins[i];
            }
        }

        static void EnterAmount()
        {
            Console.Out.WriteLine("Enter an amount : ");
            amount = int.Parse(Console.ReadLine());
        }
    }

我的问题是我不知道如何限制每个硬币的硬币数量。例如，我希望最多有4枚500欧元的硬币，6枚10欧元的硬币，5枚2欧元的硬币，等等。这真是太棒了，找零硬币会返回每个硬币使用的硬币数量。

My problem is that I don't know how to limit the quantity of coins for every coin. For exemple, I would like to have a maximum number of 4 coins of €500, 6 coins of €10, 5 coins of €2, etc. And it would be awesome that the coin change returns the number of coins used for every coin.

可以帮我吗？谢谢。

推荐答案

请注意，这段代码只是回答了有关限制谁的硬币数量的问题，但您的算法却不可行完整，因为您不需要考虑很多极端情况。

Be aware that this code just answers your question about who to limit your coins number, but your algorithm is not complete as you don't consider a lot of corner cases.

static void Main(string[] args)
{
    var amount = 100000;

    var availabeCoins = new CoinPack[] 
    { 
        new CoinPack { Value = 500, Amount = 2 },
        new CoinPack { Value = 100, Amount = 3 },
        new CoinPack { Value = 50, Amount = 5 },
        new CoinPack { Value = 20, Amount = 1 },
        new CoinPack { Value = 10, Amount = 2 },
        new CoinPack { Value = 5, Amount = 0 },
        new CoinPack { Value = 2, Amount = 10 },
        new CoinPack { Value = 1, Amount = 500 }
    };

    var usedCoins = new CoinPack[] 
    { 
        new CoinPack { Value = 500 },
        new CoinPack { Value = 100 },
        new CoinPack { Value = 50 },
        new CoinPack { Value = 20 },
        new CoinPack { Value = 10 },
        new CoinPack { Value = 5 },
        new CoinPack { Value = 2 },
        new CoinPack { Value = 1 }
    };

    for (int i = 0; i < availabeCoins.Length; i++)
    {
        usedCoins[i].Amount = amount / availabeCoins[i].Value;
        if (usedCoins[i].Amount > availabeCoins[i].Amount)
        {
            usedCoins[i].Amount = availabeCoins[i].Amount;
        }

        amount -= usedCoins[i].Amount * usedCoins[i].Value;
    }

    foreach (var usedCoin in usedCoins)
    {
        Console.WriteLine(usedCoin.Value + " " + usedCoin.Amount);
    }
}

class CoinPack
{
    public int Value;
    public int Amount;
}

UPD
效率低下，但我想它可以解决您的问题。您可以将其作为参考并自己进行改进。

UPD This solution is pretty inefficient, but I guess it solves your problem. You can take it as a reference and improve it yourself.

void Main(string[] args)
{
    var amount = 6;

    var availabeCoins = new List<CoinPack>
    { 
        new CoinPack { Value = 500, Amount = 0 },
        new CoinPack { Value = 100, Amount = 0 },
        new CoinPack { Value = 50, Amount = 0 },
        new CoinPack { Value = 20, Amount = 0 },
        new CoinPack { Value = 10, Amount = 0 },
        new CoinPack { Value = 5, Amount = 1 },
        new CoinPack { Value = 2, Amount = 3 },
        new CoinPack { Value = 1, Amount = 0 }
    };

    var usedCoins = new List<CoinPack>
    { 
        new CoinPack { Value = 500, Amount = 0 },
        new CoinPack { Value = 100, Amount = 0 },
        new CoinPack { Value = 50, Amount = 0 },
        new CoinPack { Value = 20, Amount = 0 },
        new CoinPack { Value = 10, Amount = 0 },
        new CoinPack { Value = 5, Amount = 0 },
        new CoinPack { Value = 2, Amount = 0 },
        new CoinPack { Value = 1, Amount = 0 }
    };

    if (Change(amount, availabeCoins, usedCoins) != null)
    {
        foreach (var usedCoin in usedCoins)
        {
            Console.WriteLine(usedCoin.Value + " " + usedCoin.Amount);
        }
    }
    else
    {
        Console.WriteLine("Cannot find exact change");
    }
}

List<CoinPack> Change(int amount, List<CoinPack> availableCoins, List<CoinPack> usedCoins)
{
    if (amount == 0)
    {
        return availableCoins;
    }

    if (amount < 0)
    {
        return null;
    }

    foreach (var availableCoin in availableCoins.Where(ac => ac.Amount > 0 && amount >= ac.Value))
    {
        var newAvailableCoins = CopyCoins(availableCoins);
        newAvailableCoins.First(c => c.Value == availableCoin.Value).Amount--;
        var change = Change(amount - availableCoin.Value, newAvailableCoins, usedCoins);

        if (change == newAvailableCoins)
        {
            usedCoins.First(c => c.Value == availableCoin.Value).Amount++;
            return availableCoins;
        }
    }

    return null;
}

List<CoinPack> CopyCoins(List<CoinPack> coinPacks)
{
    var copy = new List<CoinPack>();
    foreach (var coinPack in coinPacks)
    {
        copy.Add(new CoinPack { Value = coinPack.Value, Amount = coinPack.Amount });
    }
    return copy;
}

class CoinPack
{
    public int Value;
    public int Amount;
}

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