aoc/2021/day01Part2.java

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class day01Part2 {
    public static void main(String[] args) throws IOException {
        int hasIncreasedCounter = 0;
        int lineCounter = 1;

        int firstnum = 0;
        int secondnum = 0;
        int thirdnum = 0;

        int oldsum = 0;
        int newsum = 0;

        String line; // convert to int or something

        BufferedReader in = new BufferedReader(new FileReader("day01-input.txt"));

        line = in.readLine();
        while (line != null) {

            if (lineCounter == 1) { // first lines in file
                firstnum = Integer.valueOf(line).intValue();
            }
            else if (lineCounter == 2) {
                secondnum = Integer.valueOf(line).intValue();
            }
            else if (lineCounter == 3) {
                thirdnum = Integer.valueOf(line).intValue();
            }
            else {
                oldsum = firstnum + secondnum + thirdnum;

				// swapping done here
                firstnum = secondnum;
                secondnum = thirdnum;
				// read new line as thirdnum
                thirdnum = Integer.valueOf(line).intValue();

                newsum = firstnum + secondnum + thirdnum;

                System.out.println("Comparing " + oldsum + " and " + newsum);

                if (newsum > oldsum) {
                    System.out.println("Yes!");
                    hasIncreasedCounter++;
                }
                else {
                    System.out.println("Not bigger");
                }

                // oldsum = newsum; // swap to continue
            }

            lineCounter++;
            // continue
            line = in.readLine();
        }
        in.close(); // bye

        System.out.println("Final is " + hasIncreasedCounter);

    }
}