void Part_two_example_two()
        {
            var day19     = new AdventOfCode.Year2015.Day19();
            var reactions = day19.GetReactions(inputPartTwo);
            var answer    = day19.GetStepsToMolecule("HOHOHO", reactions.reverseReactions);

            Assert.Equal(6, answer);
        }
        void Part_one_example_two()
        {
            var day19     = new AdventOfCode.Year2015.Day19();
            var reactions = day19.GetReactions(inputPartOne);
            var answer    = day19.GetDistinctReactionCount("HOHOHO", reactions.reactions);

            Assert.Equal(7, answer);
        }