InterviewDB Experience

Song Sequence: Reconstruct Playlist Order from Partial Overlap Clues

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Interview Experience

Problem

You are given a list of song pairs (a, b) meaning song a was played immediately before song b in a playlist. Reconstruct the full playlist order. Assume the input forms a single valid sequence with no ambiguity.

python
def reconstruct_playlist(pairs: list[tuple[str, str]]) -> list[str]:
    pass


**Input**:  pairs = [("Shape of You", "Blinding Lights"),
                 ("Blinding Lights", "Levitating"),
                 ("Levitating", "Stay")]

**Output**: ["Shape of You", "Blinding Lights", "Levitating", "Stay"]

**Input**:  pairs = [("B","C"), ("A","B"), ("C","D")]

**Output**: ["A", "B", "C", "D"]

Follow-ups

  1. How do you identify the starting song (the one that never appears as a "next" song)?
  2. What if the pairs form a cycle — how would you detect and report that?
  3. If some pairs are missing (gaps in the sequence), how do you handle discontinuous playlists?
  4. Extend to reconstruct a sequence where each pair says song a played within 2 slots before b (not necessarily immediately before). How does the problem change?

Full Details

Problem

You are given a list of song pairs (a, b) meaning song a was played immediately before song b in a playlist. Reconstruct the full playlist order. Assume the input forms a single valid sequence with no ambiguity.

python
def reconstruct_playlist(pairs: list[tuple[str, str]]) -> list[str]:
    pass


**Input**:  pairs = [("Shape of You", "Blinding Lights"),
                 ("Blinding Lights", "Levitating"),
                 ("Levitating", "Stay")]

**Output**: ["Shape of You", "Blinding Lights", "Levitating", "Stay"]

**Input**:  pairs = [("B","C"), ("A","B"), ("C","D")]

**Output**: ["A", "B", "C", "D"]

Follow-ups

  1. How do you identify the starting song (the one that never appears as a "next" song)?
  2. What if the pairs form a cycle — how would you detect and report that?
  3. If some pairs are missing (gaps in the sequence), how do you handle discontinuous playlists?
  4. Extend to reconstruct a sequence where each pair says song a played within 2 slots before b (not necessarily immediately before). How does the problem change?
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About This Question

This is a candidate experience report from a spotify interview during the phone round.

It covers the following topics: Coding, Onsite, Phone .

Topics

Coding Onsite Phone

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About Spotify Interview Reports

This question was reported by a candidate who interviewed at Spotify. LeakCode aggregates interview reports from 10+ sources, including 1Point3Acres, Glassdoor, LeetCode Discuss, Blind, Reddit, Indeed, and Nowcoder. Each report is translated where necessary, deduplicated against existing entries, and tagged by company, role, round type, and reporting date.

Use this question as one calibration data point, not a memorization target. Companies typically rotate their question pools every 2-4 months; the exact wording of a 2024 question may differ from what you encounter today. The underlying pattern, difficulty level, and follow-up depth at Spotify are the higher-signal extractions to take from this report.

For broader preparation context, the Spotify interview process typically includes a recruiter screen, one or two technical phone screens, and a 4-5 round on-site loop covering coding, system design (at L4+ levels), and behavioral. Reports tagged on LeakCode show the round-by-round distribution and typical difficulty calibration. To browse questions filtered by round type and seniority, use the company hub linked above.

How To Practice This Type of Question

Solve similar problems on LeetCode under timed conditions (25-35 minutes per medium difficulty). The goal is pattern recognition: recognize the underlying technique (sliding window, two-pointer, BFS, memoized recursion, etc.) within 60-90 seconds of reading. Strong candidates verbalize their hypothesis out loud before coding, then iterate based on feedback. Weak candidates dive into implementation immediately, lose time on the wrong approach, and run out of time for follow-ups.

Companies update their question pools every 2-4 months. The exact wording of any given question may have been retired by the time you interview. Focus your prep on the pattern, not the specific problem. The patterns that appear in Spotify reports consistently are the ones worth investing in; one-off niche problems are not.

During Your Spotify Round

Apply the standard interview round template: clarify requirements (2-3 minutes), state your approach out loud and confirm direction with the interviewer (3-5 minutes), code with narration (15-25 minutes), test with concrete examples including edge cases (5 minutes), discuss optimization or trade-offs if time permits (5 minutes). This template is universally accepted across FAANG and adjacent companies; deviating from it produces weaker interviewer feedback signal.

The single most predictive failure mode in Spotify reports tagged "no hire": not asking clarifying questions. Interviewers are explicitly trained to weight this. Strong candidates ask 3-5 clarifying questions even on problems that look obvious; weak candidates dive into code immediately. The clarifying-question check is often the first signal recorded in the interviewer's written notes.