Musical scales

musical_scales.java

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MusicalScaleGenerator {

    private final Map<Integer, List<Integer>> scaleTransitions = new HashMap<>();
    private final int TARGET_SUM = 12;
    private final List<List<Integer>> validScales = new ArrayList<>();

    public static void main(String[] args) {
		scaleTransitions.put(1, List.of(2, 3));
        scaleTransitions.put(2, List.of(1, 2));
        scaleTransitions.put(3, List.of(1));
        generateScales();
        System.out.println(validScales);
    }

    private static void generateScales() {
        for (int startScale = 1; startScale <= 2; startScale++) {
            exploreScaleCombinations(startScale, 0, new ArrayList<>(), startScale);
        }
    }

    private static void exploreScaleCombinations(
		int currentScale,
		int currentSum,
		List<Integer> currentPath,
		int startScale) {
        int newSum = currentSum + currentScale;
        if (newSum == TARGET_SUM && scaleTransitions.get(startScale).contains(currentScale)) {
            List<Integer> newPath = new ArrayList<>(currentPath);
            newPath.add(currentScale);
            validScales.add(newPath);
            return;
        }
        if (newSum > TARGET_SUM) return;

        for (Integer nextScale : scaleTransitions.get(currentScale)) {
            List<Integer> newPath = new ArrayList<>(currentPath);
            newPath.add(currentScale);
            exploreScaleCombinations(nextScale, newSum, newPath, startScale);
        }
    }
}