[FP/HW1] Solved first exercise and did half of second

1 files changed, 35 insertions, 0 deletions

diff --git a/Year 2/Functional Programming/hw1.rkt b/Year 2/Functional Programming/hw1.rkt
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+#lang racket
+
+;;; Задача 1
+
+(define (sum-digits n)
+  (if (= n 0)
+    0
+    (+ (sum-digits (quotient n 10)) (remainder n 10))))
+
+(define (count-specials k a b)
+  (if (or (<= k 0) (> a b))
+    0
+    (+
+      (count-specials k (add1 a) b)
+      (if (and (= (remainder a k) 0) (= (remainder (sum-digits a) k) 0))
+        1
+        0))))
+
+;;; Задача 2
+
+(define (swap-last2-digits n)
+  (+ (* (quotient n 100) 100) (* (remainder n 10) 10) (quotient (remainder n 100) 10)))
+
+(define (rotate-left n)
+  (if (< n 9)
+    n
+    (swap-last2-digits (+ (* (rotate-left (quotient n 10)) 10) (remainder n 10)))))
+
+(define (pow10 n)
+  (if (= n 0)
+    1
+    (* 10 (pow10 (sub1 n)))))
+
+(define (rotate-left-preserved n d)
+  (rotate-left (remainder n (pow10 d))))