Day 2, second solution

Author: ggb

day2_1.rkt

@@ -26,4 +26,6 @@
 (define test-inputs
   (list "abcdef" "bababc" "abbcde" "abcccd" "aabcdd" "abcdee" "ababab"))
 
-(= 12 (solve-puzzle test-inputs))
+(= 12 (solve-puzzle test-inputs))
+
+;(solve-puzzle (file->lines "day2_1-input.txt"))

day2_2.rkt

@@ -0,0 +1,31 @@
+#lang racket
+
+(require threading)
+
+(define (find-equals full-list word)
+  (~>> full-list
+       (map (λ (ele)
+                 (foldr (λ (ele acc)
+                          (if (equal? (car ele) (cdr ele))
+                              (cons (car ele) acc)
+                              acc))
+                        (list)
+                        (map cons word ele))))
+       (filter (λ (e) (= (sub1 (length word))
+                         (length e))))))
+
+(define (solve-puzzle input)
+  (let ([mapped (map string->list input)])
+    (~>> mapped
+         (map (curry find-equals mapped))
+         (filter (compose not empty?))
+         (first)
+         (flatten)
+         (list->string))))
+
+(define test-input
+  (list "abcde" "fghij" "klmno" "pqrst" "fguij" "axcye" "wvxyz"))
+
+(equal? "fgij" (solve-puzzle test-input))
+
+;(solve-puzzle (file->lines "day2_1-input.txt"))