From 6b5da750ef7134a108c6d996d14c2dd60fc62806 Mon Sep 17 00:00:00 2001
From: Thomas White <taw@physics.org>
Date: Sun, 3 Apr 2022 22:49:18 +0200
Subject: Add better read/write

---
 sudoku.scm | 87 +++++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 58 insertions(+), 29 deletions(-)

diff --git a/sudoku.scm b/sudoku.scm
index a92747b..446c420 100644
--- a/sudoku.scm
+++ b/sudoku.scm
@@ -2,6 +2,7 @@
   (srfi srfi-1)
   (srfi srfi-26)
   (ice-9 match)
+  (ice-9 textual-ports)
   (sat solver)
   (sat helpers))
 
@@ -100,6 +101,59 @@
       (iota 9))))
 
 
+(define (char->number c)
+  (match c
+         (#\0 0)
+         (#\1 1)
+         (#\2 2)
+         (#\3 3)
+         (#\4 4)
+         (#\5 5)
+         (#\6 6)
+         (#\7 7)
+         (#\8 8)
+         (#\9 9)))
+
+(define (process-line board row line)
+  (map
+    (lambda (c col)
+      (when (char-numeric? c)
+        (set-initial-value
+          board
+          col
+          row
+          (char->number c))))
+    (string->list line)
+    '(0 1 2 _ 3 4 5 _ 6 7 8)))
+
+
+(define (read-sudoku port board)
+  (process-line board 0 (get-line port))
+  (process-line board 1 (get-line port))
+  (process-line board 2 (get-line port))
+  (get-line port)
+  (process-line board 3 (get-line port))
+  (process-line board 4 (get-line port))
+  (process-line board 5 (get-line port))
+  (get-line port)
+  (process-line board 6 (get-line port))
+  (process-line board 7 (get-line port))
+  (process-line board 8 (get-line port)))
+
+
+(define (print-sudoku board vals)
+  (do ((row 0 (1+ row))) ((= row 9))
+    (do ((col 0 (1+ col))) ((= col 9))
+      (format #t "~a" (get-value board vals col row))
+      (when (or (= col 2)
+                (= col 5))
+        (display "|")))
+    (newline)
+    (when (or (= row 2)
+              (= row 5))
+      (display "-----------\n"))))
+
+
 (let ((board (make-board)))
 
   ;; Each position contains exactly one number
@@ -113,34 +167,9 @@
   (all-unique-values board (boxes))
 
   ;; Initially specified values
-  (set-initial-value board 0 0 4)
-  (set-initial-value board 0 7 5)
-  (set-initial-value board 0 8 1)
-
-  (set-initial-value board 1 1 3)
-  (set-initial-value board 1 3 2)
-
-  (set-initial-value board 2 8 4)
-
-  (set-initial-value board 3 2 7)
-  (set-initial-value board 3 6 6)
-  (set-initial-value board 3 7 2)
-
-  (set-initial-value board 4 4 8)
-  (set-initial-value board 4 5 1)
-
-  (set-initial-value board 5 6 3)
-
-  (set-initial-value board 6 0 8)
-  (set-initial-value board 6 4 4)
-
-  (set-initial-value board 7 3 6)
-  (set-initial-value board 7 6 7)
-
-  (set-initial-value board 8 0 5)
+  (read-sudoku
+    (open-input-file "input.sudoku")
+    board)
 
   (let ((vals (solve-sat)))
-    (do ((row 0 (1+ row))) ((= row 9))
-      (do ((col 0 (1+ col))) ((= col 9))
-        (format #t "~a" (get-value board vals col row)))
-      (newline))))
+    (print-sudoku board vals)))
-- 
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