adding old leetcode solutions

1 files changed, 28 insertions, 0 deletions

diff --git a/leetcode/lc-999-available-captures.rkt b/leetcode/lc-999-available-captures.rkt
new file mode 100644
index 0000000..1b1a3a9
--- /dev/null
+++ b/leetcode/lc-999-available-captures.rkt
@@ -0,0 +1,28 @@
+#lang racket
+(define/contract (num-rook-captures board)
+  (-> (listof (listof string?)) exact-integer?)
+
+  (define (get-rook-space [board-state board])
+    (for/or ([board-rank (in-list board-state)]
+             [rank (in-range 0 (length board-state))]
+             #:when (index-of board-rank "R"))
+      (list rank (index-of board-rank "R"))))
+
+  (define (check-for-capturable-pawns spaces)
+    (match spaces
+      [(list _ ... "p" "." ... "R" "." ... "p" _ ...) 2]
+      [(list _ ... "R" "." ... "p" _ ...) 1]
+      [(list _ ... "p" "." ... "R" _ ...) 1]
+      [_ 0]))
+
+  (define (check-rank rank [board-state board])
+    (let ([spaces (list-ref board-state rank)])
+      (check-for-capturable-pawns spaces)))
+
+  (define (check-file file [board-state board])
+    (let ([spaces (map (curryr list-ref file) board)])
+      (check-for-capturable-pawns spaces)))
+
+  (match (get-rook-space board)
+    [(list rank file) (+ (check-rank rank)
+                         (check-file file))]))
\ No newline at end of file