0131EasyMathStringSimulation

Drum Pattern Callouts

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Trains the technique from

This is an original problem, written from a brief that listed the technique, the difficulty, the topics, the function shape and the input bounds — none of that problem's wording, examples, hints or editorials. The link is there so you can map your practice onto the standard set.

Same function shape, different story and different numbers.

A drum teacher runs a counting drill. The class counts beats out loud from 1 up to beats, but two beat families get a spoken cue instead of a number:

a beat whose number is a multiple of 3 is called as "Tap"
a beat whose number is a multiple of 5 is called as "Thud"
a beat that is a multiple of both families is called as "TapThud"
every other beat is called by its own number, written in decimal with no padding

Return the list of callouts for the whole drill, one string per beat, in beat order. The returned list has exactly beats entries and the entry at position i describes beat i + 1.

Examples

Example 1

Input: beats = 4
Output: ["1", "2", "Tap", "4"]

Only beat 3 lands on a cue family, so the other three beats are spoken as plain numbers.

Example 2

Input: beats = 16
Output: ["1", "2", "Tap", "4", "Thud", "Tap", "7", "8", "Tap", "Thud", "11", "Tap", "13", "14", "TapThud", "16"]

Beat 15 belongs to both families, so its callout joins the two cues in that order; beats 6, 9 and 12 take the first cue and beat 10 takes the second.

Example 3

Input: beats = 1
Output: ["1"]

A one-beat drill produces a single callout, the number itself.

Constraints

1 <= beats <= 10^4

The signature

The editor is preloaded with this. It matches the parent problem's shape, so a solution that works here transfers to a judge unchanged.

Python

def drum_labels(beats: int) -> list[str]:

Java

public List<String> drumLabels(int beats)

The intended approach

Time O(n)Space O(n) for the returned list

Walk the beats once and test the combined family first, because a multiple of 15 also satisfies both single tests and would otherwise be caught early. Falling through the three residue tests leaves only the plain beats, which are stringified.

Pythonentry point: drum_labels

def drum_labels(beats):
    labels = []
    for beat in range(1, beats + 1):
        if beat % 15 == 0:
            labels.append("TapThud")
        elif beat % 3 == 0:
            labels.append("Tap")
        elif beat % 5 == 0:
            labels.append("Thud")
        else:
            labels.append(str(beat))
    return labels

The obvious version

Fill the list with every beat number as text, then stride through it twice: once every third slot writing the first cue, once every fifth slot appending or replacing. No divisibility test is performed at all.

This is not filler. It was written independently of the fast solution and the two were run against thousands of random inputs to confirm they agree — which is how the answer above is known to be right. Read it when the intended approach feels like a rabbit pulled out of a hat.

Python

def bf_drum_labels(beats):
    labels = [str(beat) for beat in range(1, beats + 1)]
    for idx in range(2, beats, 3):
        labels[idx] = "Tap"
    for idx in range(4, beats, 5):
        labels[idx] = labels[idx] + "Thud" if labels[idx] == "Tap" else "Thud"
    return labels

How this problem was checked

Reference solution executed against 7 test cases — 7 passed
3 worked examples confirmed by running the code
0 eight-word sequences shared with the parent problem's text
Agrees with an independent brute-force implementation on random inputs
Test set proven to catch deliberately broken solutions
Reviewed by a separate quality pass
Function arity matches the parent problem's

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