some racket solutions to show the folder structure

14/euler14.rkt

@@ -0,0 +1,18 @@
+#lang racket
+
+(define (longest-collatz n)
+  (let
+      ((pivot (list 0 0)))
+    (define (collatz lst)
+      (if (equal? (car lst) 1)
+      lst
+      (if (even? (car lst))
+          (collatz (cons (quotient (car lst) 2) lst))
+          (collatz (cons (+ 1 (* 3 (car lst))) lst)))))
+    (for ((i (range 1 n)))
+      (if (>= (length (collatz (list i))) (second pivot))
+          (set! pivot (list i (length (collatz (list i)))))
+          0))
+    pivot))
+
+(display (first (longest-collatz 1000000)))

25/euler25.rkt

@@ -0,0 +1,11 @@
+#lang racket
+
+(define (numdigits x)
+  (string-length (number->string x)))
+
+(define (fibs limit lst)
+  (if (equal? (numdigits (car lst)) limit)
+      (length lst)
+      (fibs limit (cons (+ (car lst) (cadr lst)) lst))))
+
+(fibs 1000 '(1 1))