sorting by language

1 files changed, 33 insertions, 0 deletions

diff --git a/racket/leetcode/lc-36-valid-sudoku.rkt b/racket/leetcode/lc-36-valid-sudoku.rkt
new file mode 100644
index 0000000..915b533
--- /dev/null
+++ b/racket/leetcode/lc-36-valid-sudoku.rkt
@@ -0,0 +1,33 @@
+#lang racket
+
+(define (pos board r c)
+  (list-ref (list-ref board r) c))
+
+(define (scan-for-duplicates array)
+  (andmap (λ (row) (not (check-duplicates row))) 
+          (map (curry filter-not (curry equal? ".")) array)))
+
+(define (check-rows board)
+  (scan-for-duplicates board))
+
+(define (check-cols board)
+  (scan-for-duplicates (apply map list board)))
+
+(define (check-boxes board)
+  (define boxes-to-lists
+    (for*/list ([r (in-list '(0 3 6))]
+                [c (in-list '(0 3 6))])
+      (for*/list ([box-r (in-range r (+ r 3))]
+                  [box-c (in-range c (+ c 3))]
+                  #:unless (equal? "." (pos board box-r box-c)))
+        (pos board box-r box-c))))
+  (scan-for-duplicates boxes-to-lists))
+
+(define/contract (is-valid-sudoku board)
+  (-> (listof (listof string?)) boolean?)
+  (and (check-rows board)
+       (check-cols board)
+       (check-boxes board)))
+
+(define valid-sudoku '[["5" "3" "." "." "7" "." "." "." "."] ["6" "." "." "1" "9" "5" "." "." "."] ["." "9" "8" "." "." "." "." "6" "."] ["8" "." "." "." "6" "." "." "." "3"] ["4" "." "." "8" "." "3" "." "." "1"] ["7" "." "." "." "2" "." "." "." "6"] ["." "6" "." "." "." "." "2" "8" "."] ["." "." "." "4" "1" "9" "." "." "5"] ["." "." "." "." "8" "." "." "7" "9"]]) 
+(define invalid-sudoku '[["8" "3" "." "." "7" "." "." "." "."] ["6" "." "." "1" "9" "5" "." "." "."] ["." "9" "8" "." "." "." "." "6" "."] ["8" "." "." "." "6" "." "." "." "3"] ["4" "." "." "8" "." "3" "." "." "1"] ["7" "." "." "." "2" "." "." "." "6"] ["." "6" "." "." "." "." "2" "8" "."] ["." "." "." "4" "1" "9" "." "." "5"] ["." "." "." "." "8" "." "." "7" "9"]])
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