G2- Data Engineer 1

Anonymous User
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Interview

Interview Experience: Python + SQL Round

I recently had an interview after clearing an aptitude test (40 questions in 15 minutes).
I got a call from HR for the first technical round (Python + SQL) - 30 mins.

🔹 Python Question

Movie Booking System

  • A theater has 200 seats.
  • Rules:
    1. Single booking → assign a random seat from available ones.
    2. Group booking → pick a random starting seat, then allocate following seats in serial order.
      • Example: If user books 3 seats, and seat 67 is randomly picked, then next seats could be 69, 71 (skipping already booked ones like 68 and 70).

I had to come up with an algorithm in Python for this.

✅ Python Solution

import random

class MovieTheater:
    def __init__(self, total_seats=200):
        # 0 = available, 1 = booked
        self.seats = [0] * total_seats
        self.total_seats = total_seats

    def get_random_available_seat(self):
        """Pick a random available seat, or return -1 if full."""
        available = [i for i, s in enumerate(self.seats) if s == 0]
        if not available:
            return -1
        return random.choice(available)

    def book_tickets(self, tickets=1):
        """Book tickets following the rules."""
        if tickets <= 0:
            return []

        booked = []

        # Case 1: Single ticket
        if tickets == 1:
            seat = self.get_random_available_seat()
            if seat == -1:
                return []
            self.seats[seat] = 1
            return [seat]

        # Case 2: Group booking
        first_seat = self.get_random_available_seat()
        if first_seat == -1:
            return []
        self.seats[first_seat] = 1
        booked.append(first_seat)

        # Find next seats in serial order, skipping already booked
        current = first_seat + 1
        while len(booked) < tickets and current < self.total_seats:
            if self.seats[current] == 0:
                self.seats[current] = 1
                booked.append(current)
            current += 1

        # If we couldn’t fulfill all requested tickets, rollback
        if len(booked) < tickets:
            for s in booked:
                self.seats[s] = 0
            return []

        return booked

🔹 SQL Question

Find the date when most people watched Movie ID = 123

Table Schema:

Booking(
   Booking_id INT,
   Booking_date DATETIME,
   Show_date DATETIME,
   Movie_id INT,
   Seat_number INT
);
SELECT Show_date, COUNT(DISTINCT Seat_number) AS viewers
FROM Booking
WHERE Movie_id = 123
GROUP BY Show_date
ORDER BY viewers DESC
LIMIT 1;
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