AOC-2025/2/Ex1.java

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

public class Ex1 {
    public static void main(String[] args) {
        File file = new File("input.txt");
        String line = null;
        long count = 0;
        try (Scanner scanner = new Scanner(file)) {
            while (scanner.hasNextLine()) {
                line = scanner.nextLine();
            }
        } catch (FileNotFoundException e) {
            System.err.println("File not found: " + e.getMessage());
        }
        String[] ranges = line.split(",");
        for (String range : ranges) {
            System.out.println("Processing range: " + range);
            String[] bounds = range.split("-");
            // Case 1: bounds same size and odd length
            if (bounds[0].length() == bounds[1].length() && bounds[0].length() % 2 == 1) 
                continue;
            // Case 2: bounds same size and even length
            else if (bounds[0].length() == bounds[1].length() && bounds[0].length() % 2 == 0) {
                // split each in half, iterate first half of first bound to first half of second bound as longs; get other halves too
                long start = Long.parseLong(bounds[0].substring(0, bounds[0].length() / 2));
                long end = Long.parseLong(bounds[1].substring(0, bounds[1].length() / 2));
                long startLow = Long.parseLong(bounds[0].substring(bounds[0].length() / 2));
                long endLow = Long.parseLong(bounds[1].substring(bounds[1].length() / 2));
                for (long i = start; i <= end; i++) {

                    if (start == end) { // you little prick.
                        if (i >= startLow && i <= endLow) {
                            System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                            count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                        }

                    } else if (i == start) {
                        if (i >= startLow) {
                            System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                            count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                        }
                    } else if (i == end) {
                        if (i <= endLow) {
                            System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                            count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                        }
                    } else {
                        System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                        count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                    }
                }
            }
            // Case 3: bounds different sizes
            else {
                // Case 3a: first odd, second even
                if (bounds[0].length() % 2 == 1 && bounds[1].length() % 2 == 0) {
                    long startNum = (long) Math.pow(10, bounds[1].length() - 1);
                    long startHigh = Long.parseLong(String.valueOf(startNum).substring(0, bounds[1].length() / 2));
                    long endHigh = Long.parseLong(bounds[1].substring(0, bounds[1].length() / 2));
                    long startLow = 0;
                    long endLow = Long.parseLong(bounds[1].substring(bounds[1].length() / 2));

                    for (long i = startHigh; i <= endHigh; i++) {

                        if (startHigh == endHigh) {
                            if (i >= startLow && i <= endLow) {
                                System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                                count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                            }
                        }

                        else if (i == startHigh) {
                            if (i >= startLow) {
                                System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                                count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                            }
                        } else if (i == endHigh) {
                            if (i <= endLow) {
                                System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                                count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                            }
                        } else {
                            System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                            count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                        }
                    }
                }

                //Case 3b: first even, second odd
                else if (bounds[0].length() % 2 == 0 && bounds[1].length() % 2 == 1) {
                    // here endnum should be highest number with same length as bound0 p.e. 1200-15000 -> endnum = 9999
                    long endNum = (long) Math.pow(10, bounds[1].length() - 1) - 1;
                    long startHigh = Long.parseLong(bounds[0].substring(0, bounds[0].length() / 2));
                    long endHigh = Long.parseLong(String.valueOf(endNum).substring(0, bounds[0].length() / 2));
                    long startLow = Long.parseLong(bounds[0].substring(bounds[0].length() / 2));
                    long endLow = Long.parseLong(String.valueOf(endNum).substring(bounds[0].length() / 2));

                    for (long i = startHigh; i <= endHigh; i++) {

                        if (startHigh == endHigh) {
                            if (i >= startLow && i <= endLow) {
                                System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                                count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                            }
                        }

                        else if (i == startHigh) {
                            if (i >= startLow) {
                                System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                                count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                            }
                        } else if (i == endHigh) {
                            if (i <= endLow) {
                                System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                                count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                            }
                        } else {
                            System.out.println("Adding: " + String.valueOf(i) + String.valueOf(i));
                            count += Long.parseLong(String.valueOf(i) + String.valueOf(i));
                        }
                    }
                }
            }
        }
        System.out.println("Count: " + count);
    }
}