Day4b.java

package aoc22;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.List;

public class Day4b {
    private static String filename = "./src/aoc22/input4.txt";
    // private static String filename = "./src/aoc22/example4.txt";

    private List<Integer> firstStarts = new ArrayList<>();
    private List<Integer> firstEnds = new ArrayList<>();
    private List<Integer> secondStarts = new ArrayList<>();
    private List<Integer> secondEnds = new ArrayList<>();

    public Day4b(List<String> input) {
        parse(input);
        System.out
                .println("Number of assignments contained within other assignment: " + calculateDuplicateAssignments());
    }

    private void parse(List<String> input) {
        for (String line : input) {
            int separatorIndex = line.indexOf(',');
            String firstAssignment = line.substring(0, separatorIndex);
            String secondAssignment = line.substring(separatorIndex + 1);

            firstStarts.add(Integer.parseInt(firstAssignment.split("-")[0]));
            firstEnds.add(Integer.parseInt(firstAssignment.split("-")[1]));
            secondStarts.add(Integer.parseInt(secondAssignment.split("-")[0]));
            secondEnds.add(Integer.parseInt(secondAssignment.split("-")[1]));
        }
    }

    private int calculateDuplicateAssignments() {
        int duplicateAssignments = 0;

        for (int i = 0; i < firstStarts.size(); i++) {
            int firstStart = firstStarts.get(i);
            int firstEnd = firstEnds.get(i);
            int secondStart = secondStarts.get(i);
            int secondEnd = secondEnds.get(i);

            if ((firstStart >= secondStart && firstStart <= secondEnd)
                    || (firstEnd >= secondStart && firstEnd <= secondEnd)
                    || (secondStart >= firstStart && secondEnd <= firstEnd)
                    || (secondEnd >= firstStart && secondEnd <= firstEnd)) {
                duplicateAssignments++;
            }
        }

        return duplicateAssignments;
    }

    public static void main(String[] args) throws IOException {
        new Day4b(Files.readAllLines(Path.of(filename)));
    }
}