From f5d44b9672dec2fc157c17e73d25e1dff29267bc Mon Sep 17 00:00:00 2001
From: LeMoonStar <webmaster@unitcore.de>
Date: Sun, 8 Dec 2024 00:33:53 +0100
Subject: [PATCH] =?UTF-8?q?=E2=9A=A1=EF=B8=8F=20Day=207:=20Performance=20b?=
 =?UTF-8?q?oost=20on=20part=202?=
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---
 src/days/d07.rs | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/days/d07.rs b/src/days/d07.rs
index 21257b8..34b165e 100644
--- a/src/days/d07.rs
+++ b/src/days/d07.rs
@@ -10,11 +10,25 @@ enum Operator {
 }
 
 impl Operator {
+    #[inline(always)]
+    fn num_digits(mut n: u64) -> u32 {
+        if n == 0 {
+            return 1;
+        }
+        let mut count = 0;
+        while n > 0 {
+            n /= 10;
+            count += 1;
+        }
+        count
+    }
+
+    #[inline(always)]
     fn calculate(&self, a: u64, b: u64) -> u64 {
         match self {
             Operator::Multiply => a * b,
             Operator::Add => a + b,
-            Operator::Concat => format!("{}{}", a, b).parse().unwrap(),
+            Operator::Concat => a * 10_u64.pow(Self::num_digits(b)) + b,
         }
     }
 }