added some solutions in racket, deuglyfied 14

10/euler10.rkt

@@ -0,0 +1,12 @@
+#lang racket
+
+(require math/number-theory)
+
+(define (primes it limit prim)
+  (if (equal? it limit)
+      prim
+      (if (prime? it)
+          (primes (+ it 1) limit (cons it prim))
+          (primes (+ it 1) limit prim))))
+
+(apply + (primes 1 2000000 (list)))

14/euler14.rkt

@@ -1,18 +1,11 @@
-#lang racket
+#lang typed/racket
 
-(define (longest-collatz n)
+(: collatz (-> Nonnegative-Integer (Listof Nonnegative-Integer)))
-  (let
+(define (collatz x)
-      ((pivot (list 0 0)))
+    (cond
-    (define (collatz lst)
+      ((equal? x 1) (list 1))
-      (if (equal? (car lst) 1)
+      ((even?  x)   (cons x (collatz (quotient x 2))))
-      lst
+      ((odd? x)     (cons x (collatz (+ 1 (* 3 x)))))
-      (if (even? (car lst))
+      (else (list))))
-          (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)))
+(argmax (λ ((x : Nonnegative-Integer)) (length (collatz x))) (range 1 1000000))

16/euler16.rkt

@@ -0,0 +1,4 @@
+#lang racket
+
+(foldl + 0 (map (λ (x) (- (char->integer x) 48))
+            (string->list (number->string (expt 2 1000)))))

30/euler30.rkt

@@ -0,0 +1,16 @@
+#lang racket
+
+
+(define (findlimit it)
+  (if (> (expt 10 it) (* it (expt 9 5)))
+      it
+      (findlimit (+ it 1))))
+
+(define (digits x)
+  (map (λ (x) (- (char->integer x) 48))
+   (string->list (number->string x))))
+
+(apply +(filter (λ (x) (equal? x
+                       (apply + (map (λ (x) (expt x 5)) (digits x)))))
+
+          (range 2 (expt 10 (findlimit 1)))))