PyCon APEC 2013 Lightning Talk

1. Fizz and Buzz
of
Computer Programs
in Python.
esehara shigeo

2. WHO
ARE
YOU?

3. Shigeo Esehara
Just a Programmer using Python
and
Love Trivial Programming

4. !! WARNING !!
I guess you get used to my funny English Speaking.
(or Programming ?)

5. OK. Ready!!

6. GO!!

7. Before,
Programmers had
“The Common Sense”...

8. SICP

9. But….

10. Jeff Atword
(ex-StackOverFlow)
wrote the essay:
Why Can't Programmers..
Program?

11. Then….

12. Now,
Programmer has
“The Common Sense”...

13. FIZZ
BUZZ

14. FizzBuzz Rule
● Write a program that prints the
numbers from 1 to 100.
● For multiples of three print “Fizz”
instead of the number
● For multiples of five print “Buzz”.
● For numbers which are multiples of
both three and five print “FizzBuzz”

15. Other Lang Example

16. Haskell :: Maybe Monads FizzBuzz
type IsFizzBuzz = Maybe String
is_n:: Integer -> Integer -> Integer
is_n x y = x `mod` y
fizz :: Integer -> Integer
fizz x = is_n x 3
buzz :: Integer -> Integer
buzz x = is_n x 5
maybe_div :: Integer -> String -> IsFizzBuzz ->
IsFizzBuzz
maybe_div 0 str m = case m of
Nothing -> Just str
Just x -> Just $ str ++ x
maybe_div _ str m = m
maybe_fizz :: Integer -> IsFizzBuzz -> IsFizzBuzz
maybe_fizz x m = maybe_div is_fizz "Fizz" m
where is_fizz = fizz x
maybe_buzz :: Integer -> IsFizzBuzz -> IsFizzBuzz
maybe_buzz x m = maybe_div is_buzz "Buzz" m
where is_buzz = buzz x
maybe_fizzbuzz :: Integer -> IsFizzBuzz -> String
maybe_fizzbuzz x m = case m of
Nothing -> show x
Just x -> x
maybe_process :: Integer -> String
maybe_process x = maybe_fizzbuzz x =<< is_fizzbuzz x
where is_fizzbuzz x = maybe_fizz x >>= maybe_buzz x
go :: (Integer -> String) -> IO ()
go f = process f 1
process :: (Integer -> String) -> Integer -> IO ()
process f 101 = putStr ""
process f x = (putStrLn $ f x) >> process f next
where next = x + 1

17. OK.

18. Real Pythonista
solves
the Problem at 3sec.

19. Basic
# begin code
for i in range(1, 100):
if (i % 15 == 0):
print "FizzBuzz"
if (i % 3 == 0):
print "Buzz"
if (i % 5 == 0):
print "Fizz"
print i
# end

20. “Are You
kidding me ?”

21. No!!

22. Real Pythonista
don’t use
“if”statement
in FizzBuzz.

23. Hint

24. FizzBuzz Structure
consist
“Loop” and “Branch”.

25. In other words ...
“Loop”
is
“Iteration”.

26. Iterator in Python ?
List.

27. 3 of multiple explession:
[1, 2, 3, 4, 5, 6, 7, 8, 9 …]

28. Fizzlize!!
[‘’, ‘’, ‘Fizz’,
‘’, ‘’, ’Fizz’,
‘’, ‘’, ’Fizz’
…]

29. More!!
[‘’, ‘’, ‘Fizz’] * 3
List can be multipication in Python.

30. “Use type conversion, Luke.”
bool(‘’) = False
int(False) = 0

31. not use “if” statements
fizz = ['', '', “Fizz”] * 50
buzz = ['', '', '', '', “Buzz”] * 50
for x in range(1, 101):
fizzbuzz = fizz[x] + buzz[x]
number = str(x) * (not bool(fizzbuzz))
print fizzbuzz + number

32. “It seems bad
because
it generates list
like *malloc*
in C language.”

33. oh...

34. Real Pythonista
use “itertools”
in FizzBuzz.

35. Pythonista like ‘itertools’.
from itertools import cycle
fizz = cycle(['', '', 'Fizz'])
buzz = cycle(['', '', '', '', '', 'Buzz'])
for i in range(1, 101):
fizzbuzz = fizz.next() + buzz.next()
fizzbuzz += (str(i) * (not bool(fizzbuzz)))
print fizzbuzz

36. But...

37. TRUE Pythonista
don’t use *“List”
in FizzBuzz.
* Strictly speaking,
“String” has “List”(= array (= char sets)) Structure,
but now, String is exception.

38. Do you think
it possible ?

39. Yes,
We Can!!

40. OK.

41. Hint

42. Loop
can be created
using “Recurtion”.

43. Recursion
def loop(start, limit):
print start
(start == limit) or loop(start + 1, limit)
loop(1, 100)

44. FizzBuzz flag
Fizz, Buzz = [Bool, Bool]

45. FizzBuzz flag
Fizz, Buzz = [
0 or 1, 0 or 1]

46. FizzBuzz flag
Number = [0, 0]
Fizz = [1, 0]
Buzz = [0, 1]
FizzBuzz = [1, 1]

47. “It seems like
binary system.”

48. Yes !! Binary System.
Number = 00 = 0
Fizz = 01 = 1
Buzz = 10 = 2
FizzBuzz = 11 = 3

49. Example :: PHP
<?php
function _00($i) { echo $i; }
function _10($i) { echo "Fizz"; }
function _01($i) { echo "Buzz"; }
function _11($i) {
echo _10($i);
echo _01($i);
}
for ($i = 1; $i < 101; $i++) {
$fizz = $i % 3 === 0; $fizz = (int) $fizz;
$fizz = (string) $fizz;
$buzz = $i % 5 === 0; $buzz = (int) $buzz;
$buzz = (string) $buzz;
$fizzbuzz = "_" . $fizz . $buzz;
$fizzbuzz($i);
echo "n";
}

50. “Use the String, Luke.”
" FizzBuzzFizzBuzz"

51. “Use the String, Luke.”
" FizzBuzzFizzBuzz"
[ 0 ][ 1 ][2 ][3 ]
* “FizzBuzz” is just only 8 string.

52. Imagine
there’s
no list..

53. No List !!
def loop(start, limit):
fizzbuzz = (not start % 3) | ((not start % 5) * 2)
print (" FizzBuzz FizzBuzz"[
fizzbuzz * 4:
(fizzbuzz + 1) * 4 + ((fizzbuzz == 3) * 4)].strip()
) or start
(start == limit) or loop(start + 1, limit)
loop(1, 100)

54. Congratulations!!

55. Thanks for
your attention.
twitter: @esehara
github.com/esehara