diff options
Diffstat (limited to 'racket/leetcode/lc-1496-path-crossing.rkt')
| -rw-r--r-- | racket/leetcode/lc-1496-path-crossing.rkt | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/racket/leetcode/lc-1496-path-crossing.rkt b/racket/leetcode/lc-1496-path-crossing.rkt new file mode 100644 index 0000000..9c1941d --- /dev/null +++ b/racket/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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