From f08bd0576acdd81ec8920d3a2326c701ee2e2197 Mon Sep 17 00:00:00 2001
From: Colin McMillen <colin@semicolin.games>
Date: Thu, 3 Dec 2020 10:58:14 -0500
Subject: [PATCH] clean up solution a bit

---
 2020/Day03.cs | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/2020/Day03.cs b/2020/Day03.cs
index b80c2b8..97d1641 100644
--- a/2020/Day03.cs
+++ b/2020/Day03.cs
@@ -10,17 +10,15 @@ namespace AdventOfCode {
   public class Day03 {
 
     static int CountTreeIntersections(string[] lines, int dx, int dy) {
-      int count = 0;
-      int x = 0;
-      int y = 0;
-      while (y < lines.Length - 1) {
-        x += dx;
-        y += dy;
+      int count = 0, x = dx, y = dy;
+      while (y < lines.Length) {
         string line = lines[y];
         char tile = line[x % line.Length];
         if (tile == '#') {
           count++;
         }
+        x += dx;
+        y += dy;
       }
       return count;
     }
@@ -32,11 +30,11 @@ namespace AdventOfCode {
 
     static long Part2() {
       string[] input = File.ReadAllLines(Util.RootDir + "day03.txt");
-      long result = CountTreeIntersections(input, 1, 1);
-      result *= CountTreeIntersections(input, 3, 1);
-      result *= CountTreeIntersections(input, 5, 1);
-      result *= CountTreeIntersections(input, 7, 1);
-      result *= CountTreeIntersections(input, 1, 2);
+      var deltas = new List<(int, int)> { (1, 1), (3, 1), (5, 1), (7, 1), (1, 2) };
+      long result = 1;
+      foreach ((int dx, int dy) in deltas) {
+        result *= CountTreeIntersections(input, dx, dy);
+      }
       return result;
     }