racket solutions for problems 6 7 and 8

6/euler6.rkt

@@ -0,0 +1,4 @@
+#lang racket
+
+(- (* (apply + (range 1 101)) (apply + (range 1 101)))
+   (foldl + 0 (map (λ (x) (* x x)) (range 1 101))))

7/euler7.rkt

@@ -0,0 +1,12 @@
+#lang racket
+
+(require math/number-theory)
+
+(define (nth-prime it n primes)
+  (if (equal? n (length primes))
+      (car primes)
+      (if (prime? it)
+          (nth-prime (+ it 2) n (cons it primes))
+          (nth-prime (+ it 2) n primes))))
+
+(nth-prime 3 10001 (list 2))

8/euler8.rkt

@@ -0,0 +1,41 @@
+#lang racket
+
+(define num
+  (map (λ (x) (- (char->integer x) 48))
+       (string->list
+   (string-replace 
+"73167176531330624919225119674426574742355349194934
+96983520312774506326239578318016984801869478851843
+85861560789112949495459501737958331952853208805511
+12540698747158523863050715693290963295227443043557
+66896648950445244523161731856403098711121722383113
+62229893423380308135336276614282806444486645238749
+30358907296290491560440772390713810515859307960866
+70172427121883998797908792274921901699720888093776
+65727333001053367881220235421809751254540594752243
+52584907711670556013604839586446706324415722155397
+53697817977846174064955149290862569321978468622482
+83972241375657056057490261407972968652414535100474
+82166370484403199890008895243450658541227588666881
+16427171479924442928230863465674813919123162824586
+17866458359124566529476545682848912883142607690042
+24219022671055626321111109370544217506941658960408
+07198403850962455444362981230987879927244284909188
+84580156166097919133875499200524063689912560717606
+05886116467109405077541002256983155200055935729725
+71636269561882670428252483600823257530420752963450" "\n" ""))))
+
+(define pivot 0)
+
+(define (find-max-product n)
+  (if (< (length n) 13)
+      pivot
+      (if (> (apply * (take n 13)) pivot)
+          (begin
+            (set! pivot (apply * (take n 13)))
+            (find-max-product (cdr n)))
+          (find-max-product (cdr n)))))
+
+(find-max-product num)
+
+