Zepto SDE-1 Bangalore 2025: Air Traffic Controller LLD to Hiring Manager Rejection

TL;DR. Applied to Zepto SDE-1 through Instahyre with a "High" Insta score. Three rounds. Round 1 (DSA, 1 hour): solved Capacity to Ship Packages Within D Days and Count Days Without Meetings, both LeetCode problems, cleared. Round 2 (LLD, 1 hour): designed an Air Traffic Controller system with airplane types, runway allocation, and gate management based on Cartesian distance, cleared. Round 3 (Hiring Manager): discussed work experience, TDD (Test-Driven Deployment), and solved a Lowest Common Ancestor coding problem. Rejected. Negative feedback from the hiring manager despite clearing both technical rounds. Source linked at the bottom.

This is not a "Zepto interview prep guide." This is one specific candidate's specific 2025 loop, with the exact LeetCode problems, the exact LLD prompt (Air Traffic Controller, which you will not find in any standard prep list), and the exact point where technical ability was not enough.

The verified candidate

The candidate, Rishi Raj, applied through Instahyre, one of the recruiter-mediated platforms popular in the Indian startup ecosystem. A "High" Insta score means the platform's algorithm flagged the candidate as a strong match for the role based on profile signals: skills, experience, and activity. Getting a "High" score on Instahyre is itself a filter; it means your profile competes well against the platform's candidate pool.

The rejection came at Round 3, the Hiring Manager round, after clearing both technical rounds. This is the pattern that frustrates candidates the most: proving technical competence and still being rejected on non-technical criteria.

The Instahyre channel

Zepto, like most Indian quick-commerce and growth-stage startups, sources candidates through multiple channels: direct career page applications, LinkedIn recruiter outreach, employee referrals, and recruiter platforms like Instahyre, Naukri, and Cutshort.

Instahyre uses a scoring system. Candidates with a "High" score get faster recruiter response and direct interview scheduling. The scoring factors include: technology match (does your stack match the job requirement), experience band (are you in the right YOE range), activity signals (are you actively seeking), and market demand (how scarce is your skill set). A "High" score does not guarantee an interview, but it significantly increases the likelihood.

For Zepto SDE-1, the typical candidate profile on Instahyre is: 1 to 3 years of experience, backend or full-stack, comfortable with at least one of Java, Python, Go, or Node.js, and familiar with system design basics.

Round 1: Problem-Solving (DSA), 1 hour

Problem 1: Capacity to Ship Packages Within D Days

Given an array of package weights and a number of days D, find the minimum capacity of a ship such that all packages can be shipped in order within D days. The packages must be shipped in the order they appear (you cannot reorder).

This is a "binary search on the answer" problem. You binary search on the possible ship capacity values. The lower bound is the maximum single package weight (the ship must at least carry the heaviest package). The upper bound is the sum of all weights (one day, ship everything). For each candidate capacity, simulate the shipping process greedily: load packages until adding the next package would exceed capacity, then start a new day. If the total days needed is less than or equal to D, the capacity is feasible. Minimize over all feasible capacities.

Time complexity: O(n * log(sum of weights)). The candidate solved this cleanly.

Problem 2: Count Days Without Meetings

Given a number of working days and a list of meeting intervals, count the days that have no meetings scheduled. The approach: merge overlapping meeting intervals, then compute the gaps between merged intervals plus the days before the first meeting and after the last meeting.

The merging step is standard: sort intervals by start time, iterate through them, merge overlapping or adjacent intervals. Then subtract the total covered days from the total working days.

Time complexity: O(n log n) for the sort. The candidate solved this as well.

Both problems cleared. The DSA round was a pass. Neither problem was unusual or particularly tricky. At SDE-1 level, solving two medium LeetCode problems in 60 minutes is the expected baseline.

Round 2: Low-Level Design (1 hour)

The problem: Air Traffic Controller system

This is not a standard LLD problem. Parking Lot, BookMyShow, Splitwise, Elevator, Snake and Ladder: these are the problems every candidate prepares. Air Traffic Controller is none of those.

The system requirements (reconstructed from source details):

1. Airplane types. Different aircraft categories: small (single-engine), medium (regional jet), large (wide-body). Each type has different runway requirements (length, surface type) and gate requirements (bridge vs. remote stand).
2. Runway allocation. Multiple runways with different capabilities. A small aircraft can use any runway. A large aircraft requires a long runway. Allocation must consider current runway occupancy, approach direction, and scheduling. When multiple runways are available, select the optimal one based on a strategy (e.g., minimize taxi distance).
3. Gate management based on Cartesian distance. This is the unusual element. Gates are positioned on a 2D grid (Cartesian coordinates). When an aircraft lands and needs a gate, the system should assign the nearest available gate to the landing runway. "Nearest" is Euclidean distance on the 2D plane: sqrt((x2-x1)^2 + (y2-y1)^2).

Expected class hierarchy:

Aircraft (abstract)
  ├── SmallAircraft
  ├── MediumAircraft
  └── LargeAircraft

Runway
  - id, length, surfaceType, currentStatus (free/occupied)
  - canAccommodate(Aircraft): boolean

Gate
  - id, position (x, y), gateType (bridge/remote), currentStatus (free/occupied)
  - distanceTo(Runway): double

AirTrafficController
  - runways: List<Runway>
  - gates: List<Gate>
  - allocateRunway(Aircraft): Runway
  - allocateGate(Aircraft, Runway): Gate
  - releaseRunway(Runway): void
  - releaseGate(Gate): void

AllocationStrategy (interface)
  ├── NearestGateStrategy
  └── MinimizeTaxiTimeStrategy

The Cartesian distance component is what makes this problem non-standard. Most LLD problems deal with entity relationships and state management. This one adds a computational geometry dimension: given a list of gates with (x, y) coordinates and a runway with its own position, find the nearest available gate. The data structure choice matters: for a small number of gates, a linear scan works. For a large airport with hundreds of gates, a KD-tree or spatial index is more efficient.

The candidate cleared this round. Designing a system you have never seen before, under time pressure, is the real LLD test. Anyone can reproduce a Parking Lot from memory. Building an Air Traffic Controller from requirements demonstrates actual design ability.

Round 3: Hiring Manager, the rejection round

The Hiring Manager round at Zepto combines three elements: work experience interrogation, a technical concept discussion, and a coding problem.

Work experience discussion. The interviewer probed the candidate's past projects, role in the team, ownership level, and impact. At SDE-1 level, the interviewer is looking for: did you own a feature end-to-end, or did you implement what someone else designed? Did you make technical decisions, or did you follow instructions? The difference between "I worked on the payments service" and "I redesigned the retry mechanism for the payments service, reducing failed transactions from 3.2% to 0.4%" is the difference between advancing and not advancing.

TDD (Test-Driven Deployment). The interviewer discussed TDD principles: writing tests before implementation, the red-green-refactor cycle, and how TDD applies in a fast-moving startup environment where requirements change weekly. The question is not "do you know what TDD is" but "have you practiced it in production, and can you articulate when TDD is valuable and when it slows you down?"

For context: Zepto ships features at quick-commerce speed. Their deployment cadence is multiple times per day. TDD is not academic at Zepto; it is a deployment safety net. An engineer who cannot articulate when to write tests first and when to skip them (for prototype code that will be rewritten) does not match Zepto's operational culture.

Lowest Common Ancestor (LCA). A classic tree problem. Given a binary tree and two nodes, find their lowest common ancestor. The standard approach: recursively traverse the tree. If the current node is one of the target nodes, return it. If one target is in the left subtree and the other in the right subtree, the current node is the LCA. Time complexity O(n).

The candidate solved the LCA problem but received "negative feedback from the hiring manager." The source does not specify the exact failure point, but the pattern is clear: the work experience discussion or the TDD conversation did not demonstrate the ownership and communication depth the hiring manager was looking for.

Why technical clearance is not enough at startups

This interview illustrates a pattern that recurs across Indian startups (Zepto, Swiggy, Meesho, CRED, Razorpay): clearing the technical rounds is necessary but not sufficient for an offer.

At FAANG companies, the interview process is structured to minimize interviewer subjectivity. Bar Raisers, rubrics, and hiring committees standardize the decision. At startups, the Hiring Manager has disproportionate weight. The HM is often the person you would report to. Their evaluation is: "do I want this person on my team for the next 12 months?"

The HM evaluation criteria that are not explicitly stated but consistently applied:

1. Communication clarity. Can you explain your past work in a structured way without rambling? SDE-1 candidates who take 5 minutes to explain a simple feature lose points.
2. Ownership signal. "We built X" vs. "I designed Y and it reduced Z by N%." The interviewer is listening for first-person ownership, not team-level generalities.
3. Speed-of-learning signal. At Zepto, the codebase and product change weekly. The HM wants to know: if I give you an unfamiliar system tomorrow, how fast will you become productive? This is evaluated through the TDD discussion and the work experience interrogation.
4. Cultural fit with urgency. Quick-commerce operates on urgency. The HM is looking for energy, not just competence. A technically correct but low-energy candidate may be rejected in favor of a slightly less technical but high-ownership, high-urgency candidate.

Real questions asked in this loop

1. Capacity to Ship Packages Within D Days (LeetCode 1011): binary search on the answer, greedy simulation for feasibility check.
2. Count Days Without Meetings (LeetCode 3169): interval merging, gap computation.
3. Air Traffic Controller LLD: airplane type hierarchy, runway allocation with constraints, gate management with Cartesian distance calculation, allocation strategy pattern.
4. TDD discussion: red-green-refactor cycle, when TDD is valuable vs. when it slows down, application in high-frequency deployment environments.
5. Lowest Common Ancestor (LeetCode 236): recursive tree traversal, O(n) time.
6. Work experience deep-dive: ownership, impact quantification, technical decision-making.

Why clearing technicals is not enough at startups

1. Prepare for non-standard LLD problems. Air Traffic Controller, Ride Matching Engine, Notification Dispatcher, Food Delivery Order Router. These appear at Indian startups more than the standard Western LLD list. If you can only solve Parking Lot and BookMyShow, you are not prepared for startup LLD rounds.
2. The Hiring Manager round is not a formality. At startups, the HM has veto power. Prepare your work experience narrative as carefully as you prepare DSA. Use the STAR method (Situation, Task, Action, Result), but make Action and Result specific and quantified.
3. Know TDD beyond the definition. "Write tests before code" is the textbook answer. The startup answer is: "I write tests first for core business logic (payment flows, order state machines) and skip TDD for prototype code that I will rewrite in 2 weeks." The nuance is the signal.
4. Instahyre "High" score is a good starting signal, not a guarantee. It gets you the interview faster, but the interview bar is the same. Use Instahyre for the access, not as a quality signal about your readiness.
5. Quick-commerce interviews weight urgency and ownership more than FAANG does. If your interview demeanor is careful and measured, dial up the energy. Show that you operate at speed, not just at quality. The two are not mutually exclusive, and the HM is evaluating for both simultaneously.

Source and verification

This analysis is based on a published interview experience on Medium by Rishi Raj, describing a Zepto SDE-1 interview in Bangalore, 2025. The source includes: role (SDE-1), application channel (Instahyre, "High" score), round structure (3 rounds), specific problems (Capacity to Ship Packages, Count Days Without Meetings, Air Traffic Controller, LCA), LLD entities (airplane types, runways, gates, Cartesian distance), HM topics (TDD, work experience), and the explicit rejection outcome with negative HM feedback.

Original article: SDE-1 Interview Experience @ Zepto

PapersAdda verification standard: publicly accessible URL, per-round detail, named problems, and explicit outcome. This source meets all four criteria.

Questions about Zepto's hiring process

What is Zepto SDE-1 CTC in Bangalore? Zepto SDE-1 compensation in Bangalore for 2025 hires is typically ₹25 to ₹40 LPA. This includes base salary (₹18 to ₹25 LPA), ESOPs, and joining bonus. The range is wide because Zepto adjusts aggressively based on candidate profile and competing offers.

How many rounds does Zepto SDE-1 have? Three rounds after the initial application: DSA (1 hour), LLD (1 hour), Hiring Manager (varies). Some candidates report a fourth round (Bar Raiser) depending on the team. The candidate in this experience had three rounds.

Is Instahyre a good channel for Zepto? Yes. Zepto actively recruits through Instahyre, LinkedIn, and employee referrals. Instahyre is particularly effective for SDE-1 and SDE-2 candidates because the platform's scoring algorithm pre-qualifies candidates, reducing the initial screening overhead for Zepto's recruitment team.

Can you get rejected after clearing all technical rounds? Yes. This experience is proof. The Hiring Manager round evaluates ownership, communication, cultural fit, and operational speed. A technically strong candidate who does not demonstrate these qualities can be rejected despite clearing DSA and LLD.

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• The startup offer that worked: CRED SDE-2 Bangalore 2024: Payment Processor Machine Coding to Offer, a full loop clearance at a comparable startup
• FAANG comparison at the same level: Amazon SDE-1 Onsite 2026: Tier-2 Engineer's Real 4-Round Loop, how the SDE-1 bar differs at Amazon
• Google L4 counterpoint: Google L4 Bangalore April 2025: Topological Sort to 12-Month Cooldown, rejection at a different scale