AoC 2020.2 p2

4 files changed, 57 insertions, 16 deletions

diff --git a/password-philosophy/README.org b/password-philosophy/README.org
index 2ceb22c..15d87ab 100644
--- a/password-philosophy/README.org
+++ b/password-philosophy/README.org
@@ -31,3 +31,7 @@ The password verification method has changed:
 #+end_example
 
 Now, the "range" corresponds to two indices (indexed from 1). Of these indices, exactly one needs to be the given CHAR.
+
+*** Method
+
+See implementation. Simply, we add a wrapper to the valid-password? function that refines the inputs before calling valid-password? as usual.
diff --git a/password-philosophy/main.scm b/password-philosophy/main.scm
index fd62ba8..fa142a3 100644
--- a/password-philosophy/main.scm
+++ b/password-philosophy/main.scm
@@ -12,5 +12,9 @@
 	  (loop (string-append result line "\n"))))))
 
 (define (main args)
-  (display (pp (stdin-to-str)))
+  (let ((result
+	 (if (null? (cdr args))
+	     (pp (stdin-to-str) #t)
+	     (pp (stdin-to-str) #f))))
+    (display result))
   (newline))
diff --git a/password-philosophy/pp-test.scm b/password-philosophy/pp-test.scm
index 7641c4a..f1b9c64 100644
--- a/password-philosophy/pp-test.scm
+++ b/password-philosophy/pp-test.scm
@@ -22,19 +22,19 @@
   (count-occurrences "zzf9ct5f" #\f))
 
 (test-assert "Single X"
-  (valid-password? "X" #\X '(1 . 1)))
+  (valid-password-p1? "X" #\X '(1 . 1)))
 
 (test-assert "Single X extra"
-  (valid-password? "the X marks the spot" #\X '(1 . 1)))
+  (valid-password-p1? "the X marks the spot" #\X '(1 . 1)))
 
 (test-assert "Double X allowed"
-  (valid-password? "X lots of bad things use the logo of just an X" #\X '(1 . 2)))
+  (valid-password-p1? "X lots of bad things use the logo of just an X" #\X '(1 . 2)))
 
 (test-assert "Double X forced"
-  (valid-password? "X lots of bad things use the logo of just an X" #\X '(2 . 2)))
+  (valid-password-p1? "X lots of bad things use the logo of just an X" #\X '(2 . 2)))
 
 (test-assert "Double X failed"
-  (not (valid-password? "lots of bad things use the logo of just an X" #\X '(2 . 2))))
+  (not (valid-password-p1? "lots of bad things use the logo of just an X" #\X '(2 . 2))))
 
 (test-equal "Parse line 1"
   '("abcde" #\a (1 . 3))
@@ -48,25 +48,40 @@
   0
   (pp "1-3 a: bcde
 1-3 b: cdefg
-2-9 c: cccccccccc"))
+2-9 c: cccccccccc" #t))
 
 (test-equal "Count valid 1"
   1
   (pp "1-3 a: abcde
 1-3 b: cdefg
-2-9 c: cccccccccc"))
+2-9 c: cccccccccc" #t))
 
 (test-equal "Count valid 2"
   2
   (pp "1-3 a: abcde
 1-3 b: cdefg
-2-9 c: ccccccccc"))
+2-9 c: ccccccccc" #t))
 
 (test-equal "Count valid 3"
   3
   (pp "1-3 a: abcde
 1-3 b: cdbfg
-2-9 c: ccccccccc"))
+2-9 c: ccccccccc" #t))
+
+(test-assert "First char matched"
+  (valid-password-p2? ":)" #\) '(1 . 2)))
+
+(test-assert "Neither chars matched"
+  (not (valid-password-p2? ":(" #\) '(1 . 2))))
+
+(test-assert "Example 1"
+  (valid-password-p2? "abcde" #\a '(1 . 3)))
+
+(test-assert "Example 2"
+  (not (valid-password-p2? "cdefg" #\b '(1 . 3))))
+
+(test-assert "Example 3"
+  (not (valid-password-p2? "cccccccccc" #\a '(2 . 9))))
 
 
 (test-end "harness")
diff --git a/password-philosophy/pp.scm b/password-philosophy/pp.scm
index 9431ffa..b1d92d7 100644
--- a/password-philosophy/pp.scm
+++ b/password-philosophy/pp.scm
@@ -3,15 +3,20 @@
   #:export (pp
 	    parse-line
 	    count-occurrences
-	    valid-password?))
+	    valid-password-p1?
+	    valid-password-p2?))
 
-(define (pp str)
+(define (pp str p1?)
   (count (lambda (x) x)
 	 (map (lambda (line)
 		(let ((parsed (parse-line line)))
-		  (valid-password? (car parsed)
-				   (cadr parsed)
-				   (caddr parsed))))
+		  (if p1?
+		      (valid-password-p1? (car parsed)
+					  (cadr parsed)
+					  (caddr parsed))
+		      (valid-password-p2? (car parsed)
+					  (cadr parsed)
+					  (caddr parsed)))))
 	      (string-split
 	       (string-trim-both str char-set:whitespace)
 	       #\newline))))
@@ -29,7 +34,20 @@ into a workable datastructure:
 	  (cons (car range)
 		(cadr range)))))
 
-(define (valid-password? passwd char range)
+(define (valid-password-p2? passwd char range)
+  "Wrapper for valid-password-p1?.
+Prepares the input by indexing RANGE
+into PASSWD, setting that as the new
+PASSWD, and setting RANGE to (1 . 1)
+
+Note the original problem specifies
+that strings are NOT zero-indexed!"
+  (valid-password-p1? (string (string-ref passwd (1- (car range)))
+			      (string-ref passwd (1- (cdr range))))
+		      char
+		      '(1 . 1)))
+
+(define (valid-password-p1? passwd char range)
   "Given PASSWD, checks that CHAR appears
 within RANGE number of times. RANGE is a
 cons pair."