Thursday, 24 September 2026

Past

Three rungs, one idea. Solving rung 1 counts. Climb as far as you can.

Counting Down

while loops + counting down

Rung 1Daily goal5 points

All the way to one

Write a function called countdown

Return a list counting down from start to 1, so 5 gives [5, 4, 3, 2, 1]. If start is 0 or a negative number there is nothing to count, so return an empty list.

Examples

Input	Output
5	[5, 4, 3, 2, 1]
1	[1]
0	[]
-3	[]

There are extra hidden tests, so make it work in general, not just for these.

Rung 2Bonus7 points

Bigger jumps

Write a function called countdown_by

Now take away step each time instead of 1, and keep every number that is still above 0. So 10 with a step of 3 gives [10, 7, 4, 1]. step is always 1 or more. If start is 0 or less, return an empty list.

Examples

Input	Output
10, 3	[10, 7, 4, 1]
10, 4	[10, 6, 2]
5, 1	[5, 4, 3, 2, 1]
0, 2	[]

There are extra hidden tests, so make it work in general, not just for these.

Rung 3Bonus10 points

Leave some out

Write a function called countdown_skipping

Count down from start to 1 one number at a time, but leave out every number that divides exactly by skip. With a skip of 3 you would drop 9, 6 and 3. skip is always 2 or more. Careful: this is not the same as jumping by skip.

Examples

Input	Output
10, 3	[10, 8, 7, 5, 4, 2, 1]
5, 2	[5, 3, 1]
0, 2	[]
4, 5	[4, 3, 2, 1]

There are extra hidden tests, so make it work in general, not just for these.

Finish Rung 1 and today counts. Rungs 2 and 3 are there if you want to push further.