From 6e4e0bed012e6a1247d556c29ec68e50d85db19a Mon Sep 17 00:00:00 2001
From: Mistivia <i@mistivia.com>
Date: Sun, 25 Feb 2024 22:23:52 +0800
Subject: solve day 11 part I

---
 11/1.rkt | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 11/1.rkt

diff --git a/11/1.rkt b/11/1.rkt
new file mode 100644
index 0000000..449f8b9
--- /dev/null
+++ b/11/1.rkt
@@ -0,0 +1,70 @@
+#lang racket
+
+(require "../lib/utils.rkt")
+
+(define lines
+  (call-with-input-file "input"
+    (λ (fp) (get-lines fp))))
+
+(set! lines (list->vector lines))
+
+(define (expand-rows lines)
+  (let loop ((cur (vector->list lines)) (ret '()))
+    (if (null? cur)
+      (list->vector (reverse ret))
+      (if (andmap (λ (c) (char=? c #\.)) (string->list (car cur)))
+        (loop (cdr cur) (cons (car cur) (cons (car cur) ret)))
+        (loop (cdr cur) (cons (car cur) ret))))))
+
+(define (transpose linesvec)
+  (define lines (vector->list linesvec))
+  (define width (string-length (vector-ref linesvec 0)))
+  (define new-lines (make-vector width))
+  (let loop ((i 0))
+    (if (>= i width)
+      new-lines
+      (let ()
+        (define char-list (map (λ (l) (string-ref l i)) lines))
+        (vector-set! new-lines i (list->string char-list))
+        (loop (+ i 1))))))
+
+(define universe
+  (transpose (expand-rows (transpose (expand-rows lines)))))
+
+(define height (vector-length universe))
+(define width (string-length (vector-ref universe 0)))
+
+(define (get-galaxies universe)
+  (define (char-at x y) (string-ref (vector-ref universe y) x))
+  (let loop ((x 0) (y 0) (ret '()))
+    (if (>= y height)
+      (list->vector (reverse ret))
+      (if (>= x width)
+        (loop 0 (+ y 1) ret)
+        (if (char=? #\# (char-at x y))
+          (loop (+ x 1) y (cons (cons x y) ret))
+          (loop (+ x 1) y ret))))))
+
+(define galaxies (get-galaxies universe))
+
+(define (gen-pairs n)
+  (let loop ((i 0) (j 1) (ret '()))
+    (if (>= i n)
+      (reverse ret)
+      (if (>= j n)
+        (loop (+ 1 i) (+ 2 i) ret)
+        (loop i (+ 1 j) (cons (cons i j) ret))))))
+
+
+
+(define (distance n1 n2)
+  (define x1 (car (vector-ref galaxies n1)))
+  (define x2 (car (vector-ref galaxies n2)))
+  (define y1 (cdr (vector-ref galaxies n1)))
+  (define y2 (cdr (vector-ref galaxies n2)))
+  (+ (abs (- x1 x2)) (abs (- y1 y2))))
+
+(apply
+  +
+  (map (λ (x) (distance (car x) (cdr x)))
+       (gen-pairs (vector-length galaxies))))
\ No newline at end of file
-- 
cgit v1.0