問題1.11 ;反復 (define (ex111 n) (cond ((< n 3) n) (else (+ (ex111 (- n 1)) (* 2 (ex111 (- n 2))) (* 3 (ex111 (- n 3))))))) ;再帰 (define (ex111r n) (if (< n 3) n (ex111r-iter 2 1 0 n))) (define (ex111r-iter a b c count) (if (< count 3) a …