From 425acc5de5bda37e2152ba79058cf9d5e7ef021e Mon Sep 17 00:00:00 2001
From: Ben Harris <ben@tilde.team>
Date: Mon, 18 Sep 2023 14:48:24 -0400
Subject: [PATCH] avoid some allocations

2015 was allocating over 2gb memory in small object heap for the md5 byte conversions
---
 AOC2015/Day04.cs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/AOC2015/Day04.cs b/AOC2015/Day04.cs
index 57fcc12..cad07cb 100644
--- a/AOC2015/Day04.cs
+++ b/AOC2015/Day04.cs
@@ -33,12 +33,12 @@ public sealed class Day04 : Day
 
     public override object Part2()
     {
-        var counter = 0;
+        var counter = 9_000_000;
 
         while (true)
         {
-            var hash = MD5.HashData(Encoding.ASCII.GetBytes(_key + counter));
-            if (BitConverter.ToString(hash).Replace("-", "").StartsWith("000000"))
+            var hashBytes = MD5.HashData(Encoding.ASCII.GetBytes(_key + counter));
+            if (hashBytes[0] == 0 && hashBytes[1] == 0 && hashBytes[2] == 0)
                 return counter;
             counter++;
         }