Advent of Code Day 8 - Part 1

Day08.java

import javafx.util.Pair;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.*;

public class Day08 {

    public static void main(String[] args) {
        File file = new File("input.txt");
        if (!file.exists()) {
            System.err.println("'input.txt' does not exist");
            return;
        }

        List<Pair<Main.Instruction, Integer>> data = new ArrayList<>();

        try {
            Scanner scanner = new Scanner(file);
            while (scanner.hasNextLine()) {
                String line = scanner.nextLine();
                String[] rawData = line.split(" ");
                data.add(new Pair<>(Main.Instruction.valueOf(rawData[0].toUpperCase()), Integer.valueOf(rawData[1])));
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        // part 1
        int accumulated = 0;
        int index = 0;
        Set<Integer> alreadySeen = new HashSet<>();
        // we don't want to re-run w/ same index number
        while (!alreadySeen.contains(index)) {
            alreadySeen.add(index);
            Pair<Main.Instruction, Integer> instructionStep = data.get(index);
            switch (instructionStep.getKey()) {
                case NOP:
                    index++;
                    break;
                case ACC:
                    index++;
                    accumulated += instructionStep.getValue();
                    break;
                case JMP:
                    index += instructionStep.getValue();
                    break;
            }
        }

        System.out.println(accumulated);
    }


    enum Instruction {
        ACC,
        JMP,
        NOP;
    }
}