Problem

At input we get two integers: n, m, where 1 <= n < m <= 100000. Your program should write to output all Fibonacci numbers between n and m (including both). Numbers at output should be space separated.

Examples:

INPUT  1: 3 5
OUTPUT 1: 2 3 5

INPUT  2: 6 10
OUTPUT 2: 8 13 21 34 55

Firstly, let’s make a directory for our solution:

$ mkdir fibs
$ cd fibs

Let’s also create a testdata directory (exact name should be used) and put there some test cases:

$ mkdir testdata
$ echo '3 5' > testdata/test01.in
$ echo '2 3 5' > testdata/test01.out
$ echo '6 10' > testdata/test02.in
$ echo '8 13 21 34 55' > testdata/test02.out

Note that test inputs and outputs should have .in and .out extensions respectively.

Now let’s create our solution - we can pick any of the supported languages but for sake of this tutorial let it be Python module. Create one (empty for now):

$ touch fibs.py

We should have following files created by now:

./fibs/
./fibs/fibs.py
./fibs/testdata/
./fibs/testdata/test01.in
./fibs/testdata/test01.out
./fibs/testdata/test02.in
./fibs/testdata/test02.out

That’s it. We can now run porunga inside fibs directory and see our solution being tested against created test cases:

$ porunga test
Testing ./fibs
==============

=> Binary: python /Users/lukasz/temp/fibs/fibs.py

=> Testing ./fibs/testdata/test01.in ... Fail
=> Testing ./fibs/testdata/test02.in ... Fail

=> Total time: 0.058s
=> 2 out of 2 tests failed

Well, we get 2 tests failed but we haven’t actually coded anything yet. Just put following code into fibs.py:

import fileinput
import re
import sys


def fib(n):
    if n in (1, 2):
        return 1
    a = b = 1
    for x in range(3, n + 1):
        a, b = b, a + b
    return b

def main():
    fin = fileinput.input()
    n, m = map(int, re.findall(r'\d+', fin.readline()))
    fibs = [str(fib(num)) for num in range(n, m + 1)]
    result = ' '.join(fibs)
    sys.stdout.write(result)


if __name__ == '__main__':
    main()

(this is not optimal code as we compute Fibonacci numbers each time but it can be easily upgraded)

Let’s run tests again:

$ porunga test
Testing ./fibs
==============

=> Binary: python ./fibs/fibs.py

=> Testing ./fibs/testdata/test01.in ... OK [0.030]s
=> Testing ./fibs/testdata/test02.in ... OK [0.033]s

=> Total time: 0.063s
=> All 2 tests passed