[C#]백준/블랙잭/백트래킹

 

using System;
 
class Program
{
    private static int maxSum = int.MinValue;
 
    static void Main(string[] args)
    {
        string[] input = Console.ReadLine().Split();
        string[] input2 = Console.ReadLine().Split();
 
        int cardCount = int.Parse(input[0]);
        int targetNumber = int.Parse(input[1]);
 
        int[] cards = new int[cardCount];
 
        for (int i = 0; i < cardCount; i++)
            cards[i] = int.Parse(input2[i]);
 
        Backtracking(cards, cardCount, targetNumber, 0, 0, 0);
 
        Console.WriteLine(maxSum);
    }
 
    private static void Backtracking(int[] cards, int cardsCount, int targetNumber, int startIndex, int currentSum, int drawCount)
    {
        if (drawCount == 3)
        {
            if (currentSum <= targetNumber && currentSum > maxSum)
            {
                maxSum = currentSum;
            }
            return;
        }
 
        for (int i = startIndex; i < cardsCount; i++)
        {
            if (currentSum + cards[i] > targetNumber) continue;
 
            Backtracking(cards, cardsCount, targetNumber, i + 1, currentSum + cards[i], drawCount + 1);
        }
    }
}