; homework (define (f1 n) (do ((i 1 (+ i 1))) ((= i (* 2 n))) (display (if (< n i) (- (* 2 n) i) i))) (newline)) (display (f1 5)) (newline) (define (f2 n) (do ((i 1 (+ i 1))) ((= n i)) (display i)) (do ((i n (- i 1))) ((= 0 i)) (display i)) (newline)) (display (f2 5)) (newline) (define (f3 n) (define (f n s) (if (= n 1) (begin (display s) (newline)) (f (- n 1) (string-append (number->string (- n 1)) s (number->string (- n 1)))))) (f n (number->string n))) (display (f3 5)) (newline) (define (f4 n) (display (case n ((1) "1") ((2) "121") ((3) "12321") ((4) "1234321") ((5) "123454321") ((6) "12345654321") ((7) "1234567654321") ((8) "123456787654321") ((9) "12345678987654321"))) (newline)) (display (f4 5)) (newline)