From 0e07bd6b46093753b1563afa4db2bf73852813fc Mon Sep 17 00:00:00 2001
From: Jonni Liljamo <jonni@liljamo.com>
Date: Tue, 2 Dec 2025 15:10:29 +0200
Subject: [PATCH] feat: day2

---
 Cargo.lock               |   7 +++
 Cargo.toml               |   2 +-
 crates/common/src/lib.rs |   2 -
 crates/day2/Cargo.toml   |   7 +++
 crates/day2/src/main.rs  | 100 +++++++++++++++++++++++++++++++++++++++
 justfile                 |   5 +-
 6 files changed, 119 insertions(+), 4 deletions(-)
 create mode 100644 crates/day2/Cargo.toml
 create mode 100644 crates/day2/src/main.rs

diff --git a/Cargo.lock b/Cargo.lock
index 31151e3..f6578a0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -16,6 +16,13 @@ dependencies = [
  "common",
 ]
 
+[[package]]
+name = "day2"
+version = "0.1.0"
+dependencies = [
+ "common",
+]
+
 [[package]]
 name = "sc"
 version = "0.2.7"
diff --git a/Cargo.toml b/Cargo.toml
index 86c4459..f2246d7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,3 +1,3 @@
 [workspace]
 resolver = "3"
-members = ["crates/common", "crates/day1"]
+members = ["crates/common", "crates/day1", "crates/day2"]
diff --git a/crates/common/src/lib.rs b/crates/common/src/lib.rs
index 46e1f20..59868ec 100644
--- a/crates/common/src/lib.rs
+++ b/crates/common/src/lib.rs
@@ -31,7 +31,6 @@ impl<'a> Format<'a> {
 impl<'a> fmt::Write for Format<'a> {
     fn write_str(&mut self, s: &str) -> fmt::Result {
         if self.len > self.buf.len() {
-            write("1");
             return Err(fmt::Error);
         }
         let remaining_buf = &mut self.buf[self.len..];
@@ -40,7 +39,6 @@ impl<'a> fmt::Write for Format<'a> {
         remaining_buf[..write_num].copy_from_slice(&bytes[..write_num]);
         self.len += bytes.len();
         if write_num < bytes.len() {
-            write("2");
             return Err(fmt::Error);
         }
 
diff --git a/crates/day2/Cargo.toml b/crates/day2/Cargo.toml
new file mode 100644
index 0000000..e6e06a5
--- /dev/null
+++ b/crates/day2/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "day2"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+common = { path = "../common" }
diff --git a/crates/day2/src/main.rs b/crates/day2/src/main.rs
new file mode 100644
index 0000000..c528a7c
--- /dev/null
+++ b/crates/day2/src/main.rs
@@ -0,0 +1,100 @@
+#![no_std]
+
+use common::{format_str, print, read};
+
+fn main() {
+    let buf = [0u8; 65000];
+    read(buf.as_ptr(), buf.len());
+    let mut input = str::from_utf8(&buf).unwrap();
+    input = input.trim_end_matches(char::MIN);
+    let result_one = one(input);
+    let result_two = two(input);
+    print!(64, "one: {}\ntwo: {}\n", result_one, result_two);
+}
+
+fn one(input: &str) -> usize {
+    input
+        .split(",")
+        .map(|mut range| {
+            range = range.trim();
+            let (first, last) = range
+                .split_once("-")
+                .map(|(first, last)| (first.parse::<u64>().unwrap(), last.parse::<u64>().unwrap()))
+                .unwrap();
+
+            let mut ret = 0;
+            for i in first..=last {
+                let mut buf = [0; 20];
+                let mut i_s = format_str(&mut buf, format_args!("{}", i));
+                i_s = i_s.trim_end_matches(char::MIN);
+
+                for j in 0..i_s.len() {
+                    let mut amount = 0;
+                    let a = i_s
+                        .matches(&i_s[0..j])
+                        .map(|a| {
+                            amount += 1;
+                            a.len()
+                        })
+                        .sum::<usize>();
+                    // remove amount check to do those that repeat more times
+                    if a == i_s.len() && amount == 2 {
+                        //print!(30, "found {}\n", i);
+                        ret += i as usize;
+                        break;
+                    }
+                }
+            }
+
+            ret
+        })
+        .sum::<usize>()
+}
+
+fn two(input: &str) -> usize {
+    input
+        .split(",")
+        .map(|mut range| {
+            range = range.trim();
+            let (first, last) = range
+                .split_once("-")
+                .map(|(first, last)| (first.parse::<u64>().unwrap(), last.parse::<u64>().unwrap()))
+                .unwrap();
+
+            let mut ret = 0;
+            for i in first..=last {
+                let mut buf = [0; 20];
+                let mut i_s = format_str(&mut buf, format_args!("{}", i));
+                i_s = i_s.trim_end_matches(char::MIN);
+
+                for j in 0..i_s.len() {
+                    let a = i_s.matches(&i_s[0..j]).map(|a| a.len()).sum::<usize>();
+                    if a == i_s.len() {
+                        ret += i as usize;
+                        break;
+                    }
+                }
+            }
+
+            ret
+        })
+        .sum::<usize>()
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    const EXAMPLE_INPUT: &str = "11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124";
+
+    #[test]
+    fn example() {
+        assert_eq!(one(EXAMPLE_INPUT), 1227775554);
+        assert_eq!(two(EXAMPLE_INPUT), 4174379265);
+    }
+
+    #[test]
+    fn one_a() {
+        assert_eq!(one("3131219357-3131417388\n"), 6262562625);
+    }
+}
diff --git a/justfile b/justfile
index 855f828..ec307d4 100644
--- a/justfile
+++ b/justfile
@@ -4,5 +4,8 @@ _default:
 init day:
     cargo init crates/day{{day}}
 
+test day test="":
+    cargo test --bin day{{day}} {{test}}
+
 solve day:
-    cat input/day{{day}}.txt | cargo run day{{day}} --
+    cat input/day{{day}}.txt | cargo run --bin day{{day}} --
-- 
2.44.1