AoC 2020.1 p2

4 files changed, 101 insertions, 130 deletions

diff --git a/report-repair/combinations.scm b/report-repair/combinations.scm
new file mode 120000
index 0000000..74f5336
--- /dev/null
+++ b/report-repair/combinations.scm
@@ -0,0 +1 @@
+../combinations/combinations.scm
\ No newline at end of file
diff --git a/report-repair/main.scm b/report-repair/main.scm
index cdfed63..c6074ef 100755
--- a/report-repair/main.scm
+++ b/report-repair/main.scm
@@ -1,7 +1,4 @@
-#!/run/current-system/profile/bin/guile \
--e main -s
-!#
-
+;; -*- compile-command: "guile -L . -e main -s main.scm 3 < input.txt"; -*-
 (use-modules (rr)
 	     ((ice-9 rdelim))
 	     (ice-9 binary-ports))
@@ -15,5 +12,5 @@
 	  (loop (string-append result line " "))))))
 
 (define (main args)
-  (display (rr (stdin-to-str)))
+  (display (rr (stdin-to-str) (string->number (cadr args))))
   (newline))
diff --git a/report-repair/rr-test.scm b/report-repair/rr-test.scm
index 7d75c09..3661c64 100644
--- a/report-repair/rr-test.scm
+++ b/report-repair/rr-test.scm
@@ -5,79 +5,68 @@
 (test-begin "harness")
 
 
-(test-equal "friendship 1"
-  '(1 . 2019)
-  (return-friendship-pair 1))
-
-(test-equal "friendship 1596"
-  '(1596 . 424)
-  (return-friendship-pair 1596))
-
-(test-equal "small report"
-  '((0 . 2020)
-    (1 . 2019)
-    (2 . 2018)
-    (3 . 2017)
-    (4 . 2016)
-    (5 . 2015))
-  (report->pairs "0 1 2 3 4 5"))
-
-(test-assert "equivalent pair"
-  (equivalent-pair?
-   '(1 . 4)
-   '((5 . 6)
-     (1 . 5)
-     (3 . 7)
-     (4 . 1)
-     (6 . 2))))
-
-(test-equal "no equivalent pair"
-  #f
-  (equivalent-pair?
-   '(1 . 4)
-   '((5 . 6)
-     (1 . 5)
-     (3 . 7)
-     (6 . 2))))
-
-(test-equal "found equivalent pair"
-  '(1 . 5)
-  (return-equivalent-pair
-   '((5 . 6)
-     (1 . 5)
-     (3 . 7)
-     (5 . 1)
-     (6 . 2))))
-
-(test-error "no equivalent pairs"
+(test-equal "completed set size 1"
+  '(1 2019)
+  (make-complete-set '(2019)))
+
+(test-equal "completed set size 1"
+  '(366 675 979)
+  (make-complete-set '(675 979)))
+
+(test-equal "generate sets compatible"
+  '((675 979 366)
+    (366 979 675)
+    (979 366 675))
+  (generate-sets '(979 366 675) 3))
+
+(test-assert "does not include all"
+  (not (includes-all? '(1 2 3) '(1 2 4 5 6))))
+
+(test-assert "includes all"
+  (includes-all? '(1 2 3) '(1 2 3 5 6)))
+
+(test-error "no two inputs add to 2020"
 	    #t
-	    (return-equivalent-pair
-	     '((5 . 6)
-	       (1 . 5)
-	       (3 . 7)
-	       (6 . 2))))
+	    (get-2020-terms '(979 366 675)
+			    2))
 
-(test-equal "multiply pair 1"
-  8
-  (multiply-pair (cons 1 8)))
+(test-error "2020 not present"
+	    #t
+	    (get-2020-terms '(1 2 3)
+			    1))
+
+(test-equal "2020 is present"
+  '(2020)
+  (get-2020-terms '(2020 1 2 3)
+		  1))
+
+(test-equal "three elements which add to 2020"
+  '(675 979 366)
+  (get-2020-terms '(979 366 675)
+		  3))
 
-(test-equal "multiply pair 2"
-  24
-  (multiply-pair (cons 3 8)))
+(test-error "three elements which do not add to 2020"
+  #t
+  (get-2020-terms '(979 365 675)
+		  3))
 
-(test-equal "task-complete 1"
-  1020099
-  (rr "1009 237 791 478 1537 1011 1628"))
+(test-equal "some two elements add to 2020"
+  '(299 1721)  
+  (get-2020-terms '(1721 979 366 299 675 1456)
+		  2))
 
-(test-equal "task-complete 2"
+(test-equal "some three elements add to 2020"
+  '(675 979 366)  
+  (get-2020-terms '(1721 979 366 299 675 1456)
+		  3))
+
+(test-equal "rr wrapper 2"
   514579
-  (rr "1721
-979
-366
-299
-675
-1456
-"))
+  (rr "1721 979 366 299 675 1456" 2))
+
+(test-equal "rr wrapper 3"
+  241861950
+  (rr "1721 979 366 299 675 1456" 3))
 
 
 (test-end "harness")
diff --git a/report-repair/rr.scm b/report-repair/rr.scm
index b327d3c..6adee86 100644
--- a/report-repair/rr.scm
+++ b/report-repair/rr.scm
@@ -2,64 +2,48 @@
 -e main -s
 !#
 (define-module (rr)
+  #:use-module (combinations)
   #:use-module (srfi srfi-1)
+  #:use-module (ice-9 format)
   #:use-module (ice-9 exceptions)
   #:export (rr
-	    multiply-pair
-	    return-equivalent-pair
-	    equivalent-pair?
-	    return-friendship-pair
-	    report->pairs))
-
-
-(define (rr str)
-  (multiply-pair
-   (return-equivalent-pair
-    (report->pairs str))))
-
-(define (multiply-pair pair)
-  (* (car pair)
-     (cdr pair)))
-
-(define (return-equivalent-pair pairs)
-  "Given PAIRS friendship pairs, returns the
-ones that are found to be friends. Throws
-friendship-exception if no friends are found.
-
-We do NOT care if there are multiple pairs.
-Return the first one."
-  (let loop ((pair (car pairs)) (pairs (cdr pairs)))
-    (if (null? pairs)
-	(raise-exception
-	 (make-exception-with-message
-	  "Concerning lack of friendship!"))
-	(if (equivalent-pair? pair pairs)
-	    pair
-	    (loop (car pairs) (cdr pairs))))))
-
-(define (equivalent-pair? pair pairs)
-  "Given friendship pair PAIR and a list
-of other PAIRS, determines if PAIR is
-contained in PAIRS, irrespective of order"
-  (let ((r-pair (cons (cdr pair)
-		      (car pair))))
-    (any (lambda (pair)
-	   (equal? r-pair pair))
-	 pairs)))
-
-(define (report->pairs str)
-  "Given a report, convert it to a
-list of friendship pairs."
-  (let ((lst (string-split
-	      (string-trim-both str char-set:whitespace)
-	      char-set:whitespace)))
-    (map (lambda (str)
-	   (return-friendship-pair
-	    (string->number str)))
-	 lst)))
-
-(define (return-friendship-pair num)
-  "Given NUM, returns a cons pair with
-CAR as the original number and CDR as
-the companion number."
-  (cons num (- 2020 num)))
+	    get-2020-terms
+	    includes-all?
+	    generate-sets
+	    make-complete-set))
+
+(define (rr str len)
+  (apply * (get-2020-terms (map string->number
+				(string-split
+				 (string-trim-both str char-set:whitespace)
+				 char-set:whitespace))
+			   len)))
+
+(define (get-2020-terms lst len)
+  "Given a list of numbers, returns a list
+of length LEN whose contents add up to 2020.
+
+Throws input-exception if none are found."
+  (let loop ((sets (generate-sets lst len)))
+    (cond
+     ((null? sets) (raise-exception
+		    (make-exception-with-message
+		     (format #f "Could not find ~s arguments that add to 2020 in inputs!" len))))
+     ((includes-all? (car sets) lst) (car sets))
+     (#t (loop (cdr sets))))))
+
+(define (includes-all? lst1 lst2)
+  "Returns #t if all elements in LST1
+are present in LST2, #f otherwise."
+  (equal? lst1
+	  (lset-intersection eqv? lst1 lst2)))
+
+(define (generate-sets lst len)
+  (map make-complete-set (combinations lst (1- len))))
+
+(define (make-complete-set lst)
+  "Given a LST of numbers, i.e.
+'(979 366)
+returns a list of one greater length
+such that all numbers add up to 2020."
+  (append (list (- 2020 (apply + lst))) lst))