adding old leetcode solutions

1 files changed, 25 insertions, 0 deletions

diff --git a/leetcode/lc-1496-path-crossing.rkt b/leetcode/lc-1496-path-crossing.rkt
new file mode 100644
index 0000000..9c1941d
--- /dev/null
+++ b/leetcode/lc-1496-path-crossing.rkt
@@ -0,0 +1,25 @@
+#lang racket
+(define/contract (is-path-crossing path)
+  (-> string? boolean?)
+  (for/fold ([current-x 0]
+             [current-y 0]
+             [trail (set '(0 0))]
+             [check #false]
+             #:result check)
+            ([step (in-list (string->list path))]
+             #:break check)
+    (let*-values
+        ([(new-x new-y)
+          (case step
+            [(#\N) (values current-x (add1 current-y))]
+            [(#\S) (values current-x (sub1 current-y))]
+            [(#\E) (values (add1 current-x) current-y)]
+            [(#\W) (values (sub1 current-x) current-y)])]
+         [(new-trail-point) (list new-x new-y)])
+      (cond [(set-member? trail new-trail-point)
+             (values void void void #true)]
+            [else
+             (values new-x
+                     new-y
+                     (set-add trail new-trail-point)
+                     #false)]))))
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