LeetCode Hard Problems 25

LeetCode Hard Problems 25#

(a.k.a. The Final Boss Battle)

You’ve made it. This is where algorithms stop pretending to be nice and start testing your will to live.

Hard problems are like dark souls of coding:

  • No hand-holding.

  • No hints.

  • Just you, your logic, and your tears.

💀 What “Hard” Actually Means#

  • The question is 3 paragraphs long.

  • There’s an example that barely makes sense.

  • The top-voted solution uses math you haven’t seen since college.

  • And you start questioning your career choices.

🧩 Classic Hard Problems#

Problem

Concept

Comedy Summary

Median of Two Sorted Arrays

Binary search

“Because apparently, merging isn’t enough.”

Merge k Sorted Lists

Heaps + Linked Lists

“The Linked List multiverse.”

Trapping Rain Water

Two pointers / Stack

“When physics meets suffering.”

N-Queens

Backtracking

“The royal pain in recursion form.” 👑

Word Ladder

BFS

“Spelling bee meets Indiana Jones.”

Edit Distance

Dynamic Programming

“Fixing typos with emotional damage.”

Regular Expression Matching

Recursion + DP

“When pattern matching starts gaslighting you.”

LFU Cache

Hash map + Linked list

“When your cache has trust issues.”

Serialize and Deserialize Binary Tree

Tree traversal

“When saving data feels like therapy.”

🔥 Hard Mode Strategies#

  • Break it down. Most hard problems are just multiple easy problems in a trench coat.

  • Explain it out loud. If you can’t explain it, you don’t understand it (also, your rubber duck deserves attention).

  • Code slowly. It’s not a race. It’s algorithmic yoga.

Pro Tip: If you can solve a LeetCode Hard in under an hour, you are either:

  • a genius,

  • or you’ve seen it before. (No judgment. We’ve all “peeked.” 👀)

🧘 Final Thoughts#

LeetCode isn’t just a platform — it’s a spiritual journey. You start by learning to print “Hello World.” You end by optimizing a dynamic programming solution that nobody else understands.

But every problem teaches you something: patience, logic, humility… and the power of print() debugging.

“First you solve the problem. Then you realize… the real problem was you all along.” 💻✨

# Your code here
Contents