From d11b94c4038b16006ab8cd0522df3cd85450fdc4 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Sat, 23 Dec 2017 23:08:51 -0800
Subject: [PATCH] d24

---
 2017/d24/main.rkt  | 43 ++++++++++++++++++++++++++++++++++
 2017/d24/star1.rkt | 58 ++++++++++++++++++++++++++++++++++++++++++++++
 2017/d24/star2.rkt | 58 ++++++++++++++++++++++++++++++++++++++++++++++
 2017/d24/test1.rkt |  9 +++++++
 2017/d24/test2.rkt |  9 +++++++
 5 files changed, 177 insertions(+)
 create mode 100644 2017/d24/main.rkt
 create mode 100644 2017/d24/star1.rkt
 create mode 100644 2017/d24/star2.rkt
 create mode 100644 2017/d24/test1.rkt
 create mode 100644 2017/d24/test2.rkt

diff --git a/2017/d24/main.rkt b/2017/d24/main.rkt
new file mode 100644
index 0000000..627687b
--- /dev/null
+++ b/2017/d24/main.rkt
@@ -0,0 +1,43 @@
+#lang br/quicklang
+(require "../helper.rkt")
+(provide read-syntax (rename-out [#%mb #%module-begin]) ★ ★★)
+
+(define (read-syntax path port)
+  (define lines (port->lines port))
+  (strip-context #`(module mod "main.rkt"
+                     #,@(for/list ([datum (in-port read (open-input-string (car lines)))])
+                          datum)
+                     #,@(map (λ (ln) (apply cons (map string->number (string-split ln "/")))) (cdr lines)))))
+
+(define-macro (#%mb STARS DOMS ...)
+  #'(#%module-begin
+     (time (STARS '(DOMS ...)))))
+
+(define (find-dominoes-with-val dominoes val)
+  (filter (λ (d) (or (= (car d) val) (= (cdr d) val))) dominoes))
+
+(define (other-val-on-domino dom val)
+  ((if (= (car dom) val) cdr car) dom))
+
+(define (remove-dom doms dom)
+  (filter-not (λ (d) (equal? d dom)) doms))
+
+(define (bridges dominoes [current-val 0] [current-bridge null])
+  (define doms (find-dominoes-with-val dominoes current-val))
+  (if (null? doms)
+      (list (flatten current-bridge))
+      (append-map (λ (dom) (bridges (remove-dom dominoes dom)
+                                    (other-val-on-domino dom current-val)
+                                    (cons dom current-bridge))) doms)))
+
+(define (strongest bridges)
+  (apply max (map (λ (br) (apply + br)) bridges)))
+
+(define (★ dominoes)
+  (strongest (bridges dominoes)))
+
+(define (★★ dominoes)
+  (define brs (bridges dominoes))
+  (define maxlen (apply max (map length brs)))
+  (strongest (filter (λ (b) (= maxlen (length b))) brs)))
+                                   
diff --git a/2017/d24/star1.rkt b/2017/d24/star1.rkt
new file mode 100644
index 0000000..90d6b06
--- /dev/null
+++ b/2017/d24/star1.rkt
@@ -0,0 +1,58 @@
+#lang reader "main.rkt" ★ ; 1868
+25/13
+4/43
+42/42
+39/40
+17/18
+30/7
+12/12
+32/28
+9/28
+1/1
+16/7
+47/43
+34/16
+39/36
+6/4
+3/2
+10/49
+46/50
+18/25
+2/23
+3/21
+5/24
+46/26
+50/19
+26/41
+1/50
+47/41
+39/50
+12/14
+11/19
+28/2
+38/47
+5/5
+38/34
+39/39
+17/34
+42/16
+32/23
+13/21
+28/6
+6/20
+1/30
+44/21
+11/28
+14/17
+33/33
+17/43
+31/13
+11/21
+31/39
+0/9
+13/50
+10/14
+16/10
+3/24
+7/0
+50/50
\ No newline at end of file
diff --git a/2017/d24/star2.rkt b/2017/d24/star2.rkt
new file mode 100644
index 0000000..2948b39
--- /dev/null
+++ b/2017/d24/star2.rkt
@@ -0,0 +1,58 @@
+#lang reader "main.rkt" ★★ ; 1841
+25/13
+4/43
+42/42
+39/40
+17/18
+30/7
+12/12
+32/28
+9/28
+1/1
+16/7
+47/43
+34/16
+39/36
+6/4
+3/2
+10/49
+46/50
+18/25
+2/23
+3/21
+5/24
+46/26
+50/19
+26/41
+1/50
+47/41
+39/50
+12/14
+11/19
+28/2
+38/47
+5/5
+38/34
+39/39
+17/34
+42/16
+32/23
+13/21
+28/6
+6/20
+1/30
+44/21
+11/28
+14/17
+33/33
+17/43
+31/13
+11/21
+31/39
+0/9
+13/50
+10/14
+16/10
+3/24
+7/0
+50/50
\ No newline at end of file
diff --git a/2017/d24/test1.rkt b/2017/d24/test1.rkt
new file mode 100644
index 0000000..15c169f
--- /dev/null
+++ b/2017/d24/test1.rkt
@@ -0,0 +1,9 @@
+#lang reader "main.rkt" ★ ; 31
+0/2
+2/2
+2/3
+3/4
+3/5
+0/1
+10/1
+9/10
diff --git a/2017/d24/test2.rkt b/2017/d24/test2.rkt
new file mode 100644
index 0000000..a8da4d3
--- /dev/null
+++ b/2017/d24/test2.rkt
@@ -0,0 +1,9 @@
+#lang reader "main.rkt" ★★ ; 19
+0/2
+2/2
+2/3
+3/4
+3/5
+0/1
+10/1
+9/10