Kolikot

import java.util.Arrays;
import java.util.Scanner;
 
public class Main
{
    static int[] coinValues;
    
    public static void main(String[] args)
    {
        Scanner inputTaker = new Scanner(System.in);
        
        int amountOfCoins = inputTaker.nextInt();
        inputTaker.nextLine();
        String coinsString = inputTaker.nextLine();
        
        int[] coins = new int[amountOfCoins];
        
        /*Now the input is handled into an array*/
        String[] coinsStringArray = coinsString.split(" ");
        for(int i = 0; i < amountOfCoins; i++)
        {
            coins[i] = Integer.parseInt(coinsStringArray[i]);
        }
        
        Arrays.sort(coins);
        coinValues = coins;
        
        /*Now begins the actual calculation for the first unpresentable number*/
        int lastValueOfCoins = 1;
        
        /*i tells which number is supposed to be presented as a sum of coins*/
        for(int i = 1; true; i++)
        {
            if(coins[amountOfCoins - 1] == 0)
            {
                System.out.println(i);
                break;
            }
            
            int coinFound = -1;
            /*coinFound is the coin that proves that i can be presented as a sum
            of some coins. If it remains as -1 after the second for-loop, no
            coin is found and the current i cannot be presented as a sum of
            coins.*/
            
            for(int j = lastValueOfCoins; j <= i; j++)
            {
                int index = Arrays.binarySearch(coins, j);
                if(index >= 0)
                {
                    int firstIndex = firstIndexOf(j, index);
                    coinFound = coins[firstIndex];
                    coins[firstIndex] = 0;
                    
                    if(firstIndex + 1 < amountOfCoins) lastValueOfCoins = coins[firstIndex + 1];
                    
                    break;
                }
            }
            
            if(coinFound != -1)
            {
                i += (coinFound - 1);
            }
            else
            {
                System.out.println(i);
                break;
            }
        }
    }
    
    public static int firstIndexOf(int numberSearched, int someIndex)
    {
        int firstIndex = someIndex;
        for(int i = someIndex - 1; true; i--)
        {
            try
            {
                if(coinValues[i] == numberSearched) firstIndex = i;
                else return firstIndex;
            }
            catch(Exception e)
            {
                return firstIndex;
            }
        }
    }
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: WRONG ANSWER

Test 16

Group: 3

Verdict: ACCEPTED