How to Prepare for LeetCode: A Complete Strategy Guide for 2026

LeetCode preparation is the cornerstone of coding interview success in 2026. With thousands of problems on the platform, candidates often feel overwhelmed about where to start and how to study effectively. The difference between candidates who succeed and those who struggle is rarely raw talent. It is strategy. This guide provides a complete, actionable framework for LeetCode preparation that maximizes your learning per hour and builds the pattern recognition skills interviewers are looking for.

Why LeetCode Preparation Requires a Strategy

Randomly solving problems is the most common mistake candidates make. Without a plan, you might solve 300 problems and still freeze during an interview because you never developed transferable problem-solving patterns. A structured approach ensures that every problem you solve strengthens your ability to recognize and apply techniques to new, unseen problems.

The goal is not to memorize solutions. It is to train your brain to see a problem, identify the underlying pattern, and apply a known technique. This is exactly what interviewers evaluate. For a broader view of the full interview process, see our complete software engineer interview guide.

Phase 1: Build Your Foundation with Easy Problems

Weeks 1-3: Core Data Structures

Start with easy problems organized by data structure. Your goal is fluency with the building blocks that every algorithm relies on.

• Arrays and strings (20 problems): Traversal, searching, basic manipulation, two-pointer basics. These appear in nearly every interview.
• Hash maps and sets (10 problems): Frequency counting, lookups, duplicate detection. Hash maps are the single most useful data structure in interviews.
• Linked lists (8 problems): Traversal, reversal, fast and slow pointers, cycle detection.
• Stacks and queues (8 problems): Matching parentheses, evaluating expressions, BFS foundations.
• Trees (10 problems): Binary tree traversals (inorder, preorder, postorder), basic recursion, height and depth calculations.

At this stage, spend no more than 20-25 minutes per problem. If you cannot solve it, read the solution carefully, understand each step, then code it yourself without looking. Revisit the problem three days later.

How to Actively Learn from Each Problem

After solving or studying each problem, write a brief note answering three questions: What pattern does this problem use? How did I recognize it? What would I do differently next time? This reflection habit accelerates pattern recognition dramatically.

Phase 2: Master Medium Problems by Pattern

Weeks 4-8: Pattern-Based Practice

Medium problems are the core of most coding interviews. Organize your study by algorithm pattern rather than random topic selection.

Two Pointers (10 problems): Sorted array pair sums, container with most water, removing duplicates. The key insight is recognizing when a sorted or structured input allows you to eliminate possibilities from both ends.

Sliding Window (8 problems): Longest substring without repeating characters, minimum window substring, maximum sum subarray of size K. Look for problems asking about contiguous subarrays or substrings with constraints.

Binary Search Variations (8 problems): Search in rotated sorted array, find peak element, search a 2D matrix. Binary search applies whenever you can eliminate half the search space based on a condition.

BFS and DFS (12 problems): Number of islands, course schedule, word ladder. Graph traversal appears frequently. Practice both iterative BFS with queues and recursive DFS.

Dynamic Programming (15 problems): Start with 1D DP like climbing stairs and house robber, then progress to 2D DP like unique paths and longest common subsequence. For each problem, identify the state, the recurrence relation, and the base case.

Backtracking (8 problems): Permutations, combinations, subsets, N-queens. The template is consistent: make a choice, recurse, undo the choice.

For detailed breakdowns of each pattern with examples, read our 15 algorithm patterns guide.

The 40-Minute Rule

For medium problems, set a strict 40-minute timer. Spend the first 5 minutes understanding the problem and writing examples. Spend 5 minutes planning your approach. Spend 25 minutes coding. Spend 5 minutes testing with edge cases. If you have no working approach after 15 minutes of thinking, look at a hint or the topic tag, not the full solution.

Phase 3: Tackle Hard Problems Selectively

Weeks 9-10: Targeted Hard Problems

You do not need to solve every hard problem on LeetCode. Focus on hard problems that extend patterns you already know. Good categories include:

• Advanced sliding window: Minimum window substring variations
• Graph algorithms: Dijkstra, topological sort in complex scenarios
• Advanced DP: Interval DP, bitmask DP, DP on trees
• Segment trees and advanced data structures: Only if targeting companies known to ask them

The purpose of hard problems is to stretch your thinking, not to memorize obscure algorithms. If a hard problem uses a fundamentally new concept you have never seen, study the concept first before attempting the problem.

Phase 4: Simulate Real Interviews

Weeks 11-12: Timed Practice and Mock Interviews

The final phase transitions from learning to performing under pressure. This is where many candidates fall short because they practice in comfortable environments but freeze during actual interviews.

• Timed LeetCode contests: Participate in weekly contests to practice solving problems under time pressure with no hints
• Mock interviews: Use platforms like Pramp or Interviewing.io for peer practice. Alternatively, have a friend give you a random medium problem and explain your solution aloud
• Verbal practice: Solve problems while narrating your thought process out loud. This is a critical skill that many candidates neglect
• Random problem sets: Pick 2 random medium problems and complete them in 70 minutes total to simulate a real interview session

Make sure your resume is polished and ready before you start scheduling interviews. You want your preparation time spent on coding, not scrambling to update your resume at the last minute.

Tracking Your Progress Effectively

Maintain a spreadsheet or document to track every problem you solve. Include columns for the problem name, difficulty, pattern used, whether you solved it independently, time taken, and a date to revisit. Revisiting problems you previously struggled with is one of the most effective study techniques, yet most candidates skip it.

Spaced repetition schedule: Revisit problems you could not solve after 3 days, then after 7 days, then after 14 days. If you can solve it cleanly on the third revisit, mark it as mastered and move on.

Common LeetCode Preparation Mistakes

Mistake 1: Grinding Without Understanding

Solving 500 problems without understanding underlying patterns wastes time. Ten problems with deep understanding beat 50 solved by copying solutions.

Mistake 2: Avoiding Weak Topics

Candidates naturally gravitate toward topics they are comfortable with. If you dread graph problems or dynamic programming, those are exactly the areas that need more practice. Interviewers often test across all major categories.

Mistake 3: Never Practicing Out Loud

Writing code silently on LeetCode does not prepare you for the interactive nature of a real interview. Practice explaining your reasoning, discussing tradeoffs, and responding to follow-up questions. Refer to our data structures cheat sheet for quick refreshers on key concepts you should be able to explain verbally.

Mistake 4: Ignoring Time Complexity Analysis

Every solution you write should include a time and space complexity analysis. Interviewers always ask about this. Practice stating complexity before you start coding, as part of your approach discussion.

Mistake 5: Skipping Edge Cases

Always test your solution with empty inputs, single-element inputs, very large inputs, and inputs with duplicates or negative numbers. Handling edge cases cleanly demonstrates maturity and attention to detail.

Recommended Problem Lists and Resources

Rather than tackling all 3,000 or more LeetCode problems, use curated lists that cover the most important patterns efficiently:

• Blind 75: The original curated list of 75 essential problems covering all major topics. Ideal for candidates with limited time.
• NeetCode 150: An expanded list with better topic coverage and video explanations for each problem.
• LeetCode Top Interview Questions: The platform's own curated list based on frequency data from real interviews.
• Company-tagged problems: If targeting a specific company, filter by company tag on LeetCode to see recently asked questions.

Daily Study Schedule That Works

Consistency beats intensity. A realistic daily schedule for someone with a full-time job looks like this:

• Morning (30 min): Review one previously solved problem from your tracking sheet. Solve it again from scratch.
• Evening (60-90 min): Solve 1-2 new problems following your current phase and pattern focus.
• Weekend (2-3 hours): Participate in a LeetCode contest or do a timed mock interview session.

This adds up to roughly 10-12 hours per week, which is sustainable over a 12-week preparation period.

When You Are Ready to Interview

You are ready when you can consistently solve medium LeetCode problems within 30 minutes, explain your approach clearly, analyze time and space complexity without hesitation, and handle follow-up questions about optimization. You do not need to solve every hard problem or reach a specific number.

Start building your professional resume with EasyResume so you can begin applying to roles as your preparation reaches the interview simulation phase. The best approach is to schedule interviews with your less preferred companies first, using them as real-world practice before your top-choice interviews.