Day 88: FULL MOCK: Random

Day 88 — FULL MOCK: Random

Coding problem

Solution outline (coding)

• Treat as real onsite: no switching problems mid-thought unless stuck 5+ minutes.
• Afterward, tag each problem: pattern, time spent, off-by-one errors.
• Sleep > cram — consolidate mistakes into a short list.

Time complexity: Varies.

Space complexity: Varies.

class ReviewDay:
  """Practice / review: FULL MOCK: Random."""

  def practice_plan(self):
    return [
      "Pick 2–3 problems from this phase; re-solve timed without notes.",
      "For each: pattern name, time/space complexity, one alternative approach.",
    ]


# Input:  (your choice of problems from this week or phase)
# Output: a short list of gaps to drill before the next session

SQL interview practice

1. Interview question

Companies / track: Review / mixed (see weekly theme)

This is a review / mixed day. Expect SQL that blends data quality, funnels, and metric definitions—the same mix you see across consumer tech and ads analytics.

What you are asked to write (SQL prompt):

Review / mixed week — use the same tables and deliverables as in a standard onsite SQL round.
Random mock: generate two realistic BigQuery problem statements (analytics + reliability) and store your solutions/metrics; query for patterns in your performance.

Tables implied by the prompt:

• statements(analytics + reliability)

Engine: BigQuery — use its date, array, and approximate functions as documented.

2. Solution outline

• Clarify out loud: result grain (one row per what?), join keys, time zone, and any ORDER BY / LIMIT / tie-breakers.
• Map Mock to SQL: say the relational equivalent (e.g. hash map → GROUP BY + key; two pointers → ordered window + filter).
• Rates: SAFE_DIVIDE or NULLIF; define numerator and denominator.
• Cost: selective columns, partition pruning, avoid SELECT * when tables are huge.
• Structure: CTEs (WITH) — one step per CTE; validate on a tiny slice (counts, nulls, duplicates).

SELECT mock_id, problem_text, solution_sql FROM mock_log WHERE mock_id = 'random';