From b987f56e5dccc1d1753fa3f54fa4851b04ac43e1 Mon Sep 17 00:00:00 2001
From: Johannes <freelon@gmx.net>
Date: Sun, 8 Dec 2024 18:12:12 +0100
Subject: [PATCH] fixed day 7 concat operator where rhs is 10^x

---
 src/day07.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/day07.rs b/src/day07.rs
index 24852df..8bf9356 100644
--- a/src/day07.rs
+++ b/src/day07.rs
@@ -98,7 +98,7 @@ fn well(expected: i64, acc: i64, operands: &[i64]) -> bool {
 }
 
 fn concat(lhs: i64, rhs: i64) -> i64 {
-    let exp: u32 = (rhs as f64).log10().ceil() as u32;
+    let exp: u32 = (rhs as f64 + 1.0).log10().ceil() as u32;
     let shift = 10i64.pow(exp);
     lhs * shift + rhs
 }
@@ -130,5 +130,6 @@ mod test {
     #[test]
     fn test_concat() {
         assert_eq!(1234, concat(12, 34));
+        assert_eq!(1210, concat(12, 10));
     }
 }