Next.tech12

Maximum Depth of Binary Tree | LeetCode 104 | Python | Visually Explained

This is one of the most beginner-friendly but high-impact interview questions.
The goal:
👉 Find the maximum depth (height) of a binary tree
Simple idea:
✔ Depth = 1 + max(left, right)
✔ Use DFS (recursion) to go deep
✔ Or use BFS (level order) to count levels
Both approaches work in O(n) time.
This problem builds your foundation for:
📌 Tree recursion
📌 DFS & BFS patterns
📌 Advanced tree problems
If you understand this, you’re already ahead of most beginners 🚀
📌 Save this for revision
💬 Comment TREE if you want more binary tree problems

Inorder Traversal 🔥 The Trick That Makes Trees EASY

Most people only know recursion… but interviews expect more.
Binary Tree Inorder Traversal means:
👉 Left → Root → Right
But the real question is:
❗ Can you do it without recursion?
The smart approach uses a stack:
✔ Go left and keep pushing nodes
✔ Process node when no left remains
✔ Move to the right subtree
This helps you understand tree traversal deeply and prepares you for advanced problems.
Bonus: There’s also Morris Traversal (O(1) space) 🤯
⏱ Time Complexity: O(n)
📦 Space Complexity: O(n) (stack)
This is a core DSA concept asked in almost every interview.
📌 Save this for revision
💬 Comment TREE if you want more tree problems

1Largest Rectangle 🔥 Hard Problem Made EASY with Stack

This is one of the most feared HARD interview questions 😵‍💫
At first, people try brute force O(n²)… and fail ❌
But there’s a powerful trick using a Monotonic Stack.
The idea:
✔ Each bar expands until a smaller bar stops it
✔ Stack helps track increasing heights
✔ When a smaller bar appears → calculate max area instantly
This reduces the complexity to:
⚡ O(n) time
⚡ O(n) space
This pattern is extremely important and is used in:
📌 Histogram problems
📌 Max rectangle in matrix
📌 Stack-based optimizations
Master this and you unlock advanced DSA patterns 🔥
📌 Save this for revision
💬 Comment HARD if you want full step-by-step demo

99% People Solve This Stock Problem WRONG 😳📈

Most people lose money in stocks because they guess.

But what if I told you there’s a simple algorithm that can find the BEST time to buy and sell?

No experience needed. Just logic.

This same concept is used in real trading systems and top tech interviews.

If you understand this, you're already ahead of 90% people.

Watch till the end 🔥

Follow for more coding + real-world concepts 🚀

👉 You’re Solving Anagrams WRONG 😳 | Python Trick

Think “listen” and “silent” are different? 🤯
They are actually the SAME letters rearranged!
In this video, you’ll learn how to solve the Valid Anagram problem in Python using the fastest and simplest methods 🔥
Perfect for coding interviews, placements, and beginners!
💡 Learn: ✔️ What is an anagram
✔️ Sorting trick
✔️ Hashmap logic
✔️ Python one-line solution
🚀 Save this video & try it yourself!

🚀 Master DSA in 30 Days? The ONLY Roadmap You Need to Crack FAANG 💯

Struggling with Data Structures & Algorithms? 😵
You’re not alone.
Most people waste months watching tutorials… but still can’t solve problems.
In this video, I’ll show you the exact roadmap to master DSA step-by-step — from beginner to interview-ready 🚀
💡 Learn: ✔️ Data Structures (Arrays, Trees, Graphs)
✔️ Algorithms (Sorting, Searching, Recursion)
✔️ Problem-Solving Patterns (Sliding Window, Two Pointer)
✔️ Secret 2-Layer Revision System
🎯 If you want to crack top tech companies, this is your starting point.
👉 Start today. Stay consistent. Win big.

DSA roadmap, data structures and algorithms, DSA for beginners, coding interview preparation, FAANG preparation, LeetCode roadmap, algorithms tutorial, coding roadmap, software engineer preparation, programming roadmap, DSA strategy, coding patterns, sliding window technique, two pointer technique, tech interview tips

Anagram Check 🔥 Easiest Trick Every Coder Should Know

Most people overcomplicate this problem… but the solution is actually super simple.
Given two strings, check if they are anagrams (same characters, different order).
Example:
👉 anagram = nagaram ✅
Two smart ways to solve:
✔ Sorting Approach → Compare sorted strings
✔ Frequency Count → Count characters (faster & optimal)
⏱ Time Complexity:
Sorting → O(n log n)
Hashing → O(n)
This is a basic but very important interview question — asked in almost every company.
📌 Save this for quick revision
💬 Comment STRING if you want more string interview problems

Hardest Stack Problem? 😳 Largest Rectangle Explained in 60s (Part 2)

Struggling with LeetCode Hard problems? This one looks impossible… until you see THIS trick 👀
In this Part 2, I break down the Largest Rectangle in Histogram using a monotonic stack — step by step, visually.
💡 Learn how to:
Find max area efficiently
Understand stack push/pop logic
Crack coding interviews faster
⚡ Watch till the end — the final answer will surprise you!

Largest Rectangle 🔥 Hard Problem Made EASY with Stack

This is one of the hardest interview questions… and most people get stuck ❌
Brute force takes O(n²) — too slow.
But the real trick is using a Monotonic Stack.
💡 Key idea:
Each bar extends until a smaller bar appears on both sides
✔ Use an increasing stack
✔ When a smaller height comes → calculate area
✔ Width = distance between boundaries
That’s how we solve it in:
⚡ O(n) time
⚡ O(n) space
This pattern is VERY IMPORTANT for:
📌 Histogram problems
📌 Stack-based optimization
📌 Advanced interview questions
📌 Save this — you’ll forget it otherwise
💬 Comment HARD if you want full step-by-step demo

Longest Valid Parentheses 🔥 Stack Trick That 90% Get Wrong

This problem looks easy… but most people fail it in interviews ❌
You’re given a string of ( and )
👉 Find the longest valid (well-formed) substring
The trick?
Use a stack of indices (not characters)
✔ Push index of (
✔ When ) appears → pop
✔ Calculate length using current index
✔ Use a base index (-1) to handle edge cases
This method automatically handles:
🔥 Nested cases
🔥 Continuous valid substrings
🔥 Edge cases
⏱ Time Complexity: O(n)
📦 Space Complexity: O(n)
This is a must-know stack pattern for FAANG interviews.
📌 Save this reel for revision
💬 Comment PAREN if you want more tricky stack problems

99% People Get This SQL Question Wrong 😳🔥

Think you're good at SQL? 🤔
Try this quick challenge and comment your answer 👇
No cheating ❌ let’s test your skills 💯
Tag a friend who should try this 😏
Follow for daily coding quizzes 🚀