Method oriToIdx

app/src/main/java/solver/Utils.java:166–172

(int[] orientation, int length, boolean zeroSum)

    // orientation
    public static int oriToIdx(int[] orientation, int length, boolean zeroSum) {
        int index = 0;
        if (zeroSum) length--;
        for (int i = 0; i < length; i++)
            index = 3 * index + (orientation[i] % 3);
        return index;
    }

    public static void idxToOri(int[] orientation, int index, int length, boolean zeroSum) {
        int sum = 0;