/eight.adb

http://github.com/rtyler/euler-ada · Ada · 57 lines · 45 code · 7 blank · 5 comment · 3 complexity · b3c40c2522d1bd2f2ac88023d932e5ca MD5 · raw file

  1. --
  2. -- Project Euler problem #8
  3. --
  4. -- Find the greatest product of five consecutive digits in the 1000-digit
  5. -- number.
  6. with Ada.Text_IO;
  7. use Ada.Text_IO;
  8. procedure Eight is
  9. Source : constant String := "73167176531330624919225119674426574742355349194934" &
  10. "96983520312774506326239578318016984801869478851843" &
  11. "85861560789112949495459501737958331952853208805511" &
  12. "12540698747158523863050715693290963295227443043557" &
  13. "66896648950445244523161731856403098711121722383113" &
  14. "62229893423380308135336276614282806444486645238749" &
  15. "30358907296290491560440772390713810515859307960866" &
  16. "70172427121883998797908792274921901699720888093776" &
  17. "65727333001053367881220235421809751254540594752243" &
  18. "52584907711670556013604839586446706324415722155397" &
  19. "53697817977846174064955149290862569321978468622482" &
  20. "83972241375657056057490261407972968652414535100474" &
  21. "82166370484403199890008895243450658541227588666881" &
  22. "16427171479924442928230863465674813919123162824586" &
  23. "17866458359124566529476545682848912883142607690042" &
  24. "24219022671055626321111109370544217506941658960408" &
  25. "07198403850962455444362981230987879927244284909188" &
  26. "84580156166097919133875499200524063689912560717606" &
  27. "05886116467109405077541002256983155200055935729725" &
  28. "71636269561882670428252483600823257530420752963450";
  29. function Digits_Product (Input : in String) return Natural is
  30. Result : Natural := 1;
  31. begin
  32. for Item in Input'Range loop
  33. Result := (Result * Natural'Value (Input (Item .. Item)));
  34. end loop;
  35. return Result;
  36. end Digits_Product;
  37. Highest : Natural := 0;
  38. begin
  39. for Index in 1 .. (Source'Length - 5) loop
  40. declare
  41. Sub : constant String := Source (Index .. Index + 4);
  42. Product : constant Natural := Digits_Product (Sub);
  43. begin
  44. if Product > Highest then
  45. Highest := Product;
  46. end if;
  47. end;
  48. end loop;
  49. Put_Line ("> Highest product:" & Natural'Image (Highest));
  50. end Eight;