W Code - Pattern-Based DSA Learning Platform

Bhanu Bisht

Curated List

Top Trie Problems for Coding Interviews

Master the Trie pattern with this curated list of 5 must-solve problems. Each problem is ranked by interview frequency, difficulty, and learning value. Prefix tree for efficient string search and storage.

Ranking Criteria: Interview frequency (40%), Learning value (30%), Difficulty progression (20%), Company tag count (10%).

Ranking Methodology

We rank Trie problems using four criteria:

1.Interview Frequency (40%) — How often the problem appears in real interviews (Google, Amazon, Microsoft, etc.)

2.Learning Value (30%) — Whether solving it teaches transferable concepts

3.Difficulty Progression (20%) — Problems ordered from Easy → Medium → Hard for systematic learning

4.Company Coverage (10%) — Number of companies that actively ask this problem

Must-Solve Problems (Easy)

2 easy problems focusing on basic pattern recognition and implementation.

Pro tip: Solve these first to build confidence. Target: 15 minutes each.

Practice all Easy Trie problems on W Code with instant feedback and solution explanations.

Core Problems (Medium)

3 medium problems focusing on combining the pattern with other techniques.

Pro tip: These form the core of your interview prep. Target: 25 minutes each.

Practice all Medium Trie problems on W Code with instant feedback and solution explanations.

Advanced Problems (Hard)

2 hard problems focusing on complex variations and optimization.

Pro tip: Only attempt after mastering Medium. Target: 40 minutes with hints if needed.

Practice all Hard Trie problems on W Code with instant feedback and solution explanations.

Study Plan

Week 1: Solve all Easy problems to build pattern recognition

Week 2: Tackle Medium problems — aim for 2-3 per day

Week 3: Attempt Hard problems with 45-minute timer

Week 4: Re-solve problems you struggled with

Daily target: 2 problems minimum, 4 maximum (quality over quantity).

Use the Trie template from W Code to develop muscle memory for the pattern structure.

Tips for ${pattern.name} Problems

1.Always identify the pattern before jumping into code

2.Start with brute force, then optimize to O(L)

3.Practice explaining your approach out loud

4.Test with edge cases: empty input, single element, large n

5.Time yourself — aim for 20 minutes on Medium problems

Frequently Asked Questions

How many Trie problems should I solve?

Solve at least 5 problems to build strong pattern recognition. For FAANG prep, aim for all 5.

Which companies ask Trie questions?

Google, Amazon, Microsoft, and Meta frequently ask Trie problems. Service companies like TCS and Infosys test simpler variations.

What should I learn before Trie?

Prerequisites: Trees, Strings. Make sure you're comfortable with these first.

Practice all 5 Trie problems with AI hints and step-by-step solutions on W Code. Start free!

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Curated List