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FizzBuzz

The FizzBuzz interview question has been going around a while. If for some reason you're not familiar with it, here's one wording of it:

Write a program that prints the numbers from 1 to 100. For numbers divisible by three print "fizz" instead of the number, and for numbers divisible by five print "buzz". For numbers which are divisible by both three and five print "fizzbuzz".

Solutions using loops, recursion, if and switch statements abound. But here's my (hopefully) novel solution to this problem. It uses sed an xargs and runs in a Unix shell. It is tweetable (i.e. less than 140 chars) and uses no conditionals:

seq 5 5 100 | xargs -IX echo "Xs/[0-9]*/buzz/" > f
seq 3 3 100 | xargs -IX echo "Xs/[0-9]*/fizz/" >> f
seq 1 100 | sed -f f

Here's how it works:

  1. The first line creates sed commands to replace zero or more digits on every 5th line with the word "buzz"
  2. The second line creates sed commands to replace zero or more digits on every 3rd line with the word "fizz"
  3. The 3rd line creates a list of numbers from 1 to 100 (the seq 1 100 part) and runs all the sed commands over each that, in order.

How does 15 become "fizzbuzz" though? The trick is in the "zero or more digits" part. First sed runs 15s/[0-9]*/buzz/ which replaces all the digits with "buzz". Then sed runs 15s/[0-9]*/fizz/ which replaces the zero-length string of no digits with "fizz" but without removing the word "buzz".

The resulting output looks like this:

1
2
fizz
4
buzz
fizz
7
8
fizz
buzz
11
fizz
13
14
fizzbuzz
16
17
fizz
19
buzz
fizz
22
23
fizz
buzz
26
fizz
28
29
fizzbuzz
31
32
fizz
34
buzz
fizz
37
38
fizz
buzz
41
fizz
43
44
fizzbuzz
46
47
fizz
49
buzz
fizz
52
53
fizz
buzz
56
fizz
58
59
fizzbuzz
61
62
fizz
64
buzz
fizz
67
68
fizz
buzz
71
fizz
73
74
fizzbuzz
76
77
fizz
79
buzz
fizz
82
83
fizz
buzz
86
fizz
88
89
fizzbuzz
91
92
fizz
94
buzz
fizz
97
98
fizz
buzz

Addendum: Is this really a valid fizzbuzz solution? You tell me! It conforms to the spec, but the program doesn't really look at the values 1 to 100 on each line. Instead of the values on each line, it works with the positions of the lines.