Tech Interview Preparation: Algorithms, System Design, and Behavioral Questions

The Tech Interview Process

Tech company interviews typically consist of 4-6 stages:

1. Phone Screening (30-45 min)
2. Technical Phone Interview (45-60 min)
3. Coding Challenge (Take-home or live)
4. Onsite/Virtual Interview (3-5 hours, 4-6 rounds)
5. Hiring Manager Discussion
6. Culture Fit/Behavioral

Data Structures & Algorithms

Core Topics

Data Structures:

• Arrays and Strings
• Linked Lists
• Stacks and Queues
• Hash Tables
• Trees (Binary, BST, AVL)
• Heaps
• Graphs
• Tries

Algorithms:

• Searching (Binary Search, DFS, BFS)
• Sorting (Quick, Merge, Heap Sort)
• Dynamic Programming
• Greedy Algorithms
• Backtracking
• Divide and Conquer

Study Plan (8 Weeks)

Weeks 1-2: Array/String (15 problems), Linked List (10), Stack/Queue (10)

Weeks 3-4: Trees (15 problems), BST (10), Graph (15)

Weeks 5-6: Dynamic Programming - 1D (10), 2D (10), Advanced (5)

Week 7: Greedy (10), Backtracking (10)

Week 8: Mock interviews and review

Best Resources

• LeetCode: Blind 75 question list
• HackerRank: Interview preparation kit
• AlgoExpert: Comprehensive solutions
• Books: "Cracking the Coding Interview" by Gayle McDowell

Problem-Solving Framework

UMPIRE Method

1. Understand: Clarify inputs, outputs, edge cases
2. Match: Identify patterns and data structures
3. Plan: Write pseudocode, calculate complexity
4. Implement: Write clean, readable code
5. Review: Test edge cases, check syntax
6. Evaluate: Analyze time/space complexity, optimize

System Design Interview

Common Questions

• Design URL Shortener (TinyURL)
• Design Twitter/X
• Design YouTube
• Design WhatsApp
• Design Uber/Lyft
• Design Rate Limiter

Approach

1. Requirements (5 min): Functional vs non-functional, scale, users
2. Estimation (5 min): QPS, storage, bandwidth, cache
3. High-Level Design (10-15 min): API, database, components
4. Deep Dive (15-20 min): Scaling, bottlenecks, caching, load balancing
5. Wrap-Up (5 min): Trade-offs, monitoring, deployment

Key Concepts

Scalability: Horizontal/vertical scaling, load balancing, caching, CDN, sharding

Reliability: Replication, failover, backups

Performance: Indexing, caching, async processing, message queues

Resources: Grokking System Design, System Design Primer (GitHub), "Designing Data-Intensive Applications"

Behavioral Interview

STAR Method

Situation: Set the context

Task: Describe your responsibility

Action: Explain what you did

Result: Share the outcome

Common Questions

1. Tell me about yourself
2. Why this company?
3. Biggest strength/weakness
4. Conflict resolution example
5. Leadership experience
6. Failure and learning
7. Challenging project
8. Tight deadline experience
9. Disagreement with manager
10. Questions for interviewer

Preparation Tips

• Research company culture thoroughly
• Use their products
• Read tech blog
• Follow recent news
• Prepare questions to ask

Mock Interviews

Platforms:

• Pramp: Free peer interviews
• interviewing.io: Anonymous practice
• Gainlo: Experienced interviewers
• Exponent: System design focused

Interview Day Tips

Before

• Sleep well
• Test equipment
• Review notes
• Do final company research

During

• Think out loud
• Ask clarifying questions
• Discuss trade-offs
• Accept hints gracefully

After

• Send thank-you email (within 24 hours)
• Take notes on what went well/poorly
• Follow up on timeline

Prepare with Rejectly

Rejectly helps with:

• Company-specific CV optimization
• Skill highlighting for positions
• STAR method story creation
• Mock interview question prep

Start interview preparation

Final Thoughts

Tech interview prep is a marathon, not a sprint. Consistent practice, mock interviews, and learning from failures are key to success.

Average Prep Time:

• Entry-level: 2-3 months
• Mid-level: 1-2 months
• Senior: 3-4 weeks

Remember: Every interview is a learning opportunity!