I just made the code a little more idiomatic - avoided using the box arount max - used a named let for loop and made it terminal recursive removed the box impr

I just made the code a little more idiomatic - avoided using the box arount max - used a named let for loop and made it terminal recursive removed the box improve performance from 10s to a 9s. #lang typed/racket (struct: route ([dest : Integer] [cost : Integer]) #:transparent) (struct: node ([neighbours : (Listof route)]) #:transparent) (: str->int (String -> Integer)) (define (str->int str) (define n (string->number str)) (if n (numerator (inexact->exact (real-part n))) 0)) (: read-places (-> (Vectorof node))) (define (read-places) (define lines (file->lines "agraph")) (define num-lines (str->int (car lines))) (define nodes (build-vector num-lines (lambda (n) (node `())))) (let loop ([i : Integer 0]) (define nums (string-split (list-ref (cdr lines) i))) (define len (length nums)) (when (and (> len 2) (> (length lines) (+ i 2))) (let ([node-id (str->int (list-ref nums 0))] [neighbour (str->int (list-ref nums 1))] [cost (str->int (list-ref nums 2))]) (define new-node (node (append (node-neighbours (vector-ref nodes node-id)) (list (route neighbour cost))))) (vector-set! nodes node-id new-node) (loop (+ i 1))))) nodes) (: get-longest-path ((Vectorof node) Integer (Vectorof Boolean) -> Integer)) (define (get-longest-path nodes node-id visited) (vector-set! visited node-id #t) (define sum (foldr (lambda ([neighbour : route] [max : Integer]) (if (not (vector-ref visited (route-dest neighbour))) (let ([dist (+ (route-cost neighbour) (get-longest-path nodes (route-dest neighbour) visited))]) (if (> dist max) dist max)) max)) 0 (node-neighbours (vector-ref nodes node-id)))) (vector-set! visited node-id #f) sum) (define nodes (read-places)) (define visited : (Vectorof Boolean) (build-vector (vector-length nodes) (lambda (n) #f))) (define start (current-inexact-milliseconds)) (define len (get-longest-path nodes 0 visited)) (define duration (- (current-inexact-milliseconds) start)) (printf "~a LANGUAGE Racket ~a\n" len (inexact->exact (floor duration)))