advent-of-code-2023

commit a6412e56e85d2bd5343b60fc7d431351c52c2fce
parent df1d03bd1110063b94c895095dd5b9ea889c728a
Author: Lukas Henkel <lh@entf.net>
Date:   Wed,  6 Dec 2023 06:16:36 +0100

Day 6 task 1

Diffstat:
A
input/6.txt
 | 
2
++
M
src/day-5.lisp
 | 
9
---------
A
src/day-6.lisp
 | 
20
++++++++++++++++++++
M
src/utils.lisp
 | 
12
+++++++++++-
A
t/day-6.lisp
 | 
10
++++++++++

5 files changed, 43 insertions(+), 10 deletions(-)
diff --git a/input/6.txt b/input/6.txt
@@ -0,0 +1,2 @@
+Time:        47     98     66     98
+Distance:   400   1213   1011   1540
diff --git a/src/day-5.lisp b/src/day-5.lisp
@@ -3,15 +3,6 @@
   (:export #:day-5))
 (in-package #:aoc/day-5)
 
-(defun read-number-list (string &key (start 0))
-  (loop for i from start below (length string)
-        collect (multiple-value-bind (number end)
-                    (parse-integer string
-                                   :start i
-                                   :junk-allowed t)
-                  (setf i end)
-                  number)))
-
 (defun parse-seeds (input)
   (let ((line (prog1
                   (read-line input)
diff --git a/src/day-6.lisp b/src/day-6.lisp
@@ -0,0 +1,20 @@
+(defpackage #:aoc/day-6
+  (:use #:cl #:aoc/utils)
+  (:export #:day-6))
+(in-package #:aoc/day-6)
+
+(defun day-6 (input)
+  (let* ((line (read-line input))
+         (times (read-number-list line :start (1+ (position #\: line))))
+         (line (read-line input))
+         (distances (read-number-list line :start (1+ (position #\: line)))))
+    (loop with task-1 = nil
+          for time in times
+          for distance in distances
+          do (push (loop for speed from 1 below time
+                         for remaining-time = (- time speed)
+                         for travelled = (* speed remaining-time)
+                         when (> travelled distance)
+                           sum 1 fixnum)
+                   task-1)
+          finally (return (apply #'* task-1)))))
diff --git a/src/utils.lisp b/src/utils.lisp
@@ -16,7 +16,8 @@
    #:point-x
    #:point-y
    #:point-neighbours
-   #:do-map-neighbours))
+   #:do-map-neighbours
+   #:read-number-list))
 (in-package #:aoc/utils)
 
 (defun normalize-type (type)
@@ -160,3 +161,12 @@
                                              (push bb? checks))
                                            checks))
                               ,@body)))))))
+
+(defun read-number-list (string &key (start 0))
+  (loop for i from start below (length string)
+        collect (multiple-value-bind (number end)
+                    (parse-integer string
+                                   :start i
+                                   :junk-allowed t)
+                  (setf i end)
+                  number)))
diff --git a/t/day-6.lisp b/t/day-6.lisp
@@ -0,0 +1,10 @@
+(defpackage #:aoc-test/day-6
+  (:use #:cl #:lisp-unit2))
+(in-package #:aoc-test/day-6)
+
+(define-test test-day-6
+    ()
+  (multiple-value-bind (task-1)
+      (aoc:run-day 6 "Time:      7  15   30
+Distance:  9  40  200")
+    (assert= 288 task-1)))