(diff

 (list  ; lcs_v1
  ""
  ";; Longest Common Subsequence (LCS)"
  ";; Algoritmo ricorsivo"
  ""
  "(define lcs      ; val:  stringa"
  "  (lambda (u v)  ; u, v: stringhe"
  "    (cond ((or (= (string-length u) 0) (= (string-length v) 0))"
  "           (string ))  ; stringa vuota"
  "          ((char=? (string-ref u 0) (string-ref v 0))"
  "           (string-append"
  "            (string (string-ref u 0)) (lcs (substring u 1) (substring v 1))))"
  "          (else"
  "           (longer (lcs (substring u 1) v) (lcs u (substring v 1))))"
  "          )))"
  ""
  "(define longer   ; val:  stringa"
  "  (lambda (u v)  ; u, v: stringhe"
  "    (let ((m (string-length u)) (n (string-length v)))"
  "      (if (< m n)"
  "          v"
  "          u))"
  "    ))"
  ""
  )     ; lcs_v1

 (list  ; lcs_v2
  ""
  ";; Longest Common Subsequence (LCS)"
  ";; Algoritmo ricorsivo"
  ""
  "(define lcs      ; val:  stringa"
  "  (lambda (u v)  ; u, v: stringhe"
  "    (cond ((or (= (string-length u) 0) (= (string-length v) 0))"
  "           (string ))  ; stringa vuota"
  "          ((char=? (string-ref u 0) (string-ref v 0))"
  "           (string-append"
  "            (substring u 0 1) (lcs (substring u 1) (substring v 1))))"
  "          (else"
  "           (longer (lcs (substring u 1) v) (lcs u (substring v 1))))"
  "          )))"
  ""
  ";;  Stringa piu' lunga"
  ""
  "(define longer   ; val:  stringa"
  "  (lambda (u v)  ; u, v: stringhe"
  "    (let ((m (string-length u)) (n (string-length v)))"
  "      (cond ((< m n) v)"
  "            ((> m n) u)"
  "            ((= (random 2) 0) v)"
  "            (else u)))"
  "    ))"
  ""
  )     ; lcs_v1

 )  ; diff