aoc-2024-day01b-onepass.linq

#load "../common/aoc-input-util.linq"
#load "../common/aoc-parsers.linq"

void Main()
{
	using (var tr =
		//OpenDataFile()
		GetSampleInput()
		)
	{
		var num_scores = new Dictionary<int, (int left_count, int right_count)>();
		var total_score = 0;
		// does exactly what you think it does
		var input = RegexInputParser(tr, new Regex(@"^(\d+)\s+(\d+)$"), 
				m => (loc0: int.Parse(m.Groups[1].Value), loc1: int.Parse(m.Groups[2].Value))
			);
		foreach (var (col1, col2) in input)
		{
			// add column 1
			if (!num_scores.TryGetValue(col1, out var col1_counts))
			{
				// col1 has not appeared yet in either column
				// therefore, its contribution to the final answer is ZERO
				num_scores[col1] = (1, 0);
			}
			else
			{
				num_scores[col1] = (col1_counts.left_count + 1, col1_counts.right_count);
				// this adds col1 to the total score
				total_score += (col1 * col1_counts.right_count);
			}

			if (!num_scores.TryGetValue(col2, out var col2_counts))
			{
				// col2 has not appeared yet in either column
				// therefore, its contribution to the final answer is ZERO
				num_scores[col2] = (0, 1);
			}
			else
			{
				num_scores[col2] = (col2_counts.left_count, col2_counts.right_count + 1);
				total_score += col2 * col2_counts.left_count;
			}
			Console.WriteLine("after ({0}, {1}) total score is {2}", col1, col2, total_score);
		}
		
		total_score.Dump();
	}
}

const string EXAMPLE_1 = @"
3   4
4   3
2   5
1   3
3   9
3   3
";

TextReader GetSampleInput()
{
	return new StringReader(EXAMPLE_1);
}