From aa0f725e19787255a3464b81c6041f52dda3a768 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20M=C3=A5rdbrink?= <hugo@mardbrink.se>
Date: Tue, 2 Dec 2025 09:31:56 +0100
Subject: [PATCH] Day 2

---
 .gitignore    |  3 ++
 d02/main.odin | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 91 insertions(+)
 create mode 100644 d02/main.odin

diff --git a/.gitignore b/.gitignore
index 2250ff0..874382e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,5 @@
 # Hide inputs
 *.txt
+
+# Build files
+*.dSYM
diff --git a/d02/main.odin b/d02/main.odin
new file mode 100644
index 0000000..28662ca
--- /dev/null
+++ b/d02/main.odin
@@ -0,0 +1,88 @@
+package main
+
+import "core:fmt"
+import "core:math"
+import "core:os"
+import "core:slice"
+import "core:strconv"
+import "core:strings"
+import "core:time"
+
+import util "../util"
+
+part_1 :: proc(lines: ^[]string) {
+	result: i64 = 0
+
+	buf: [100]byte
+	for line in lines {
+		range := strings.split(line, "-")
+		lower, _ := strconv.parse_i64(range[0])
+		upper, _ := strconv.parse_i64(range[1])
+
+		for id in lower ..= upper {
+			id_str := strconv.write_int(buf[:], id, 10)
+			half_len := len(id_str) / 2
+			equal_parts := id_str[:half_len] == id_str[half_len:]
+
+			result += id if equal_parts else 0
+		}
+	}
+
+	fmt.printfln("  [Result] %v", result)
+}
+
+has_recurring_segments :: proc(id: i64) -> bool {
+	buf: [100]byte
+	id_str := strconv.write_int(buf[:], id, 10)
+
+	for seg_len in 1 ..= len(id_str) / 2 {
+		if len(id_str) % seg_len != 0 do continue
+
+		matching_pattern := true
+		for i in seg_len ..< len(id_str) {
+			if id_str[i] != id_str[i % seg_len] {
+				matching_pattern = false
+				break
+			}
+		}
+
+		if matching_pattern do return true
+	}
+	return false
+}
+
+part_2 :: proc(lines: ^[]string) {
+	result: i64 = 0
+
+	for line in lines {
+		range := strings.split(line, "-")
+		lower, _ := strconv.parse_i64(range[0])
+		upper, _ := strconv.parse_i64(range[1])
+
+		for id in lower ..= upper {
+			result += id if has_recurring_segments(id) else 0
+		}
+	}
+
+	fmt.printfln("  [Result] %v", result)
+}
+
+main :: proc() {
+	context.allocator = context.temp_allocator
+	defer free_all(context.temp_allocator)
+
+	INPUT :: #load("input.txt", string)
+	lines := strings.split(INPUT, ",")
+
+	fmt.println("[Part 1]")
+	start := time.tick_now()
+	part_1(&lines)
+	duration := time.tick_diff(start, time.tick_now())
+	fmt.printfln("  [Time]   %vns\n", time.duration_nanoseconds(duration))
+
+	fmt.printfln("[Part 2]")
+	start = time.tick_now()
+	part_2(&lines)
+	duration = time.tick_diff(start, time.tick_now())
+	fmt.printfln("  [Time]   %vns", time.duration_nanoseconds(duration))
+}