Many developers spend months grinding LeetCode and still struggle in interviews. The problem is not how much you practice — it is how you practice. In this article, you will learn the most effective study strategies, a proven study plan, and how to avoid the most common mistakes.
The Wrong Way: Random LeetCode Grinding
Random grinding means: open LeetCode, pick a problem, spend 2 hours, fail, look at the answer, move to the next problem. Repeat 300 times.
Why this does not work:
- No pattern recognition — you solve each problem as a unique puzzle
- No spaced repetition — you forget the solution within a week
- No time management — you spend too long on problems above your level
- No progression — you jump from easy to hard without mastering the fundamentals
The Right Way: Pattern-Based Practice
Instead of solving random problems, study one pattern at a time. Solve 5-10 problems per pattern. Your brain starts recognizing the pattern, and new problems become easier.
The workflow:
- Learn the pattern (read the tutorial, understand the template)
- Solve 2-3 easy problems using the pattern
- Solve 2-3 medium problems (most interview questions are medium)
- Attempt 1-2 hard problems (optional, for top companies)
- Move to the next pattern
The Blind 75 and NeetCode 150
Two curated problem lists designed for efficient interview preparation:
Blind 75: The original list. 75 problems covering all major patterns. Created by a Meta engineer. Enough for most interviews.
NeetCode 150: An expanded list with 150 problems grouped by pattern. Better organization and progression within each pattern.
Which to use:
- Short on time (4-6 weeks): Blind 75
- More time (8-12 weeks): NeetCode 150
- Targeting FAANG specifically: NeetCode 150 + extra hard problems
Spaced Repetition
Solving a problem once is not enough. You will forget the approach within days. Use spaced repetition:
| Review Schedule | When |
|---|---|
| First review | 1 day after solving |
| Second review | 3 days after first review |
| Third review | 7 days after second review |
| Fourth review | 14 days after third review |
On each review, do not look at your previous solution. Try to solve it from scratch. If you can solve it quickly, move to the next review interval. If you struggle, reset to day 1.
You can track this with a simple spreadsheet:
| Problem | Pattern | First Solved | Review 1 | Review 2 | Review 3 | Status |
|---|---|---|---|---|---|---|
| Two Sum | Hash Map | May 1 | May 2 | May 5 | May 12 | Mastered |
| 3Sum | Two Pointers | May 1 | May 2 | May 5 | - | Review needed |
The 15-Minute Rule
When you are stuck on a problem:
- First 15 minutes: Try to solve it yourself. Think about which pattern applies. Draw examples.
- After 15 minutes: Read the hint (not the full solution). Try again with the hint.
- After 30 minutes total: Read the editorial or a clean solution. Understand why it works.
- After reading: Close the solution. Implement it yourself from memory.
- Next day: Solve it again without looking at anything.
Never spend more than 45 minutes on a single problem during practice. In a real interview, you have 30-45 minutes total, so you need to be efficient.
Time-Boxing Practice
Simulate interview conditions:
| Phase | Time | What to Do |
|---|---|---|
| Read and understand | 3 min | Read the problem, identify constraints |
| Plan | 5 min | Identify the pattern, explain your approach |
| Code | 15 min | Write the solution |
| Test | 5 min | Walk through test cases, fix bugs |
| Analyze | 2 min | State time and space complexity |
| Total | 30 min |
If you cannot finish in 30 minutes, it is okay. But track your time. The goal is to get faster over weeks of practice.
Weekly Study Plan (8 Weeks)
This plan covers all major patterns using the NeetCode 150 as a base.
Week 1: Arrays + Hashing + Two Pointers
- Learn: Two Pointers pattern, Hash Map pattern
- Solve: Two Sum, Valid Anagram, Group Anagrams, Two Sum II, 3Sum, Container With Most Water
- Problems: 10-12
Week 2: Sliding Window + Binary Search
- Learn: Sliding Window template, Binary Search templates
- Solve: Longest Substring Without Repeating, Best Time to Buy/Sell Stock, Binary Search, Search in Rotated Sorted Array
- Problems: 10-12
Week 3: Stack + Linked List
- Learn: Monotonic Stack, Fast/Slow Pointers
- Solve: Valid Parentheses, Daily Temperatures, Reverse Linked List, Linked List Cycle
- Problems: 10-12
Week 4: Trees
- Learn: Tree DFS, Tree BFS patterns
- Solve: Invert Binary Tree, Maximum Depth, Same Tree, Binary Tree Level Order, Validate BST
- Problems: 10-12
Week 5: Graphs + Heap
- Learn: BFS/DFS on graphs, Heap pattern
- Solve: Number of Islands, Clone Graph, Course Schedule, Kth Largest Element, Top K Frequent
- Problems: 10-12
Week 6: Backtracking + DP (Part 1)
- Learn: Backtracking template, Linear DP
- Solve: Subsets, Permutations, Combination Sum, Climbing Stairs, House Robber, Coin Change
- Problems: 10-12
Week 7: DP (Part 2) + Greedy
- Learn: 2D DP, Knapsack, Greedy
- Solve: Unique Paths, LCS, Edit Distance, Word Break, Jump Game, Meeting Rooms
- Problems: 10-12
Week 8: Review + Mock Interviews
- Review: Revisit all problems marked as “difficult” or “needs review”
- Mock: 3-4 timed mock interviews (30 min each)
- Fill gaps: Focus on your weakest pattern
- Problems: 10-15 (all reviews)
Total: ~80-90 problems in 8 weeks at ~10 hours/week
Mock Interviews
Practicing alone is not enough. You need to practice explaining your solution to another person.
Options:
- Pramp — free mock interviews with other developers
- Interviewing.io — practice with engineers from FAANG (paid)
- Study buddy — find a partner and interview each other weekly
- Rubber duck — explain your solution out loud to yourself (better than nothing)
In mock interviews, practice:
- Thinking out loud
- Asking clarifying questions
- Discussing trade-offs
- Handling hints gracefully
What to Do When You Get Stuck on a Pattern
If a pattern feels impossible:
- Go back to easier problems. Solve 3-5 easy problems in that pattern before attempting medium.
- Read multiple explanations. Different people explain things differently. NeetCode videos, editorial sections, and discussion posts all offer different perspectives.
- Write the brute force first. Even if it is O(n^2), getting a working solution builds confidence. Then optimize.
- Skip and return. If you are stuck after 2-3 problems in a pattern, move to another pattern and come back later.
Common Mistakes
Spending too long on one problem. Use the 15-minute rule. Your time is better spent on more problems.
Not reviewing solved problems. Solving once and moving on means you forget within a week. Use spaced repetition.
Skipping easy problems. Easy problems build pattern recognition. Solve at least 2-3 easy problems per pattern before medium.
Only solving in one language. Pick one language for interviews and stick with it. Do not switch between Python and Kotlin.
Not reading the editorial. After solving (or failing to solve) a problem, always read the editorial. You might find a better approach.
Comparing yourself to others. Everyone learns at a different pace. Focus on your own progress.
Studying the night before. DSA preparation takes weeks, not hours. Start early and be consistent.
Tracking Your Progress
Use a spreadsheet or Notion to track:
- Problem name and number
- Pattern category
- Difficulty (easy/medium/hard)
- Solved independently? (yes/no/with hints)
- Time taken
- Review dates
- Notes (key insight, common mistake)
After 4 weeks, you should see:
- Easy problems: solved in 5-10 minutes
- Medium problems: solved in 15-25 minutes
- Hard problems: partial solution or solved with hints
After 8 weeks:
- Medium problems: solved in 10-20 minutes
- You recognize patterns within the first 2-3 minutes
- You can explain your approach before coding
What’s Next?
You now have a study plan. The final article in this series is the DSA Cheat Sheet — all data structures, algorithms, patterns, and code templates in one reference page.
Next: DSA Tutorial #25: DSA Cheat Sheet
Full series: DSA from Zero to Interview Ready