From e309f81f40a2d01513060f7bd07daaeb5ae78ad6 Mon Sep 17 00:00:00 2001
From: Matias Linares <matias@deprecated.org>
Date: Mon, 2 Dec 2024 08:53:23 -0300
Subject: Add 2 day of 2024 (part1)

---
 2024/aoc-utils.scm  |  8 +++++++-
 2024/day02/main.scm | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 1 deletion(-)
 create mode 100755 2024/day02/main.scm

diff --git a/2024/aoc-utils.scm b/2024/aoc-utils.scm
index 6b57aa5..7fafcc6 100644
--- a/2024/aoc-utils.scm
+++ b/2024/aoc-utils.scm
@@ -3,9 +3,15 @@
   #:use-module (srfi srfi-9)
   #:use-module (ice-9 regex)
   #:use-module (ice-9 rdelim)
-  #:export (file->list))
+  #:export (file->list
+            lines->number-list))
 
 (define (file->list filename)
   (let ((lines (string-split (call-with-input-file filename read-string) #\Newline)))
     ; Remove EOF token
     (take lines (1- (length lines)))))
+
+(define (lines->number-list lines)
+  (map (lambda (line)
+         (map string->number (string-split line #\Space)))
+       lines))
diff --git a/2024/day02/main.scm b/2024/day02/main.scm
new file mode 100755
index 0000000..310f72e
--- /dev/null
+++ b/2024/day02/main.scm
@@ -0,0 +1,54 @@
+#!/usr/bin/guile -s
+!#
+
+(add-to-load-path (format #f "~a/2024" (getcwd)))
+(add-to-load-path (format #f "~a/.." (dirname (current-filename))))
+
+(use-modules
+ (aoc-utils)
+ (srfi srfi-1)
+ (srfi srfi-9)
+ (ice-9 regex))
+
+(define (all-decresing? report)
+  (equal? report (sort report >)))
+
+(define (all-incrising? report)
+  (equal? report (sort report <)))
+
+(define (safe-head? report)
+  (if (>=(length report) 2)
+      (let ((diff (abs (- (first report) (second report)))))
+        (and (<= diff 3) (>= diff 1)))
+      #t))
+
+(define (safe-difference? report)
+  (cond ((not (safe-head? report)) #f)
+        ((null? report) #t)
+        (else (safe-difference? (cdr report)))))
+
+(define (safe-report? report)
+  (and (or (all-incrising? report)
+           (all-decresing? report))
+       (safe-difference? report)))
+
+(define (part1 lines)
+  (let ((reports (lines->number-list lines)))
+    (fold + 0 (map (lambda (report) (if (safe-report? report)
+                                        1
+                                        0)) reports))))
+
+(define (part2 lines)
+  (let ((reports (lines->number-list lines)))
+    0))
+
+(define (main)
+  (let ((lines (file->list "input.txt")))
+    (display "Part1: ")
+    (display (part1 lines))
+    (newline)
+    (display "Part2: ")
+    (display (part2 lines))
+    (newline)))
+
+(main)
-- 
cgit v1.2.3-70-g09d2