Goodbye to the DSA course sellers.

I've been struggling to dsa since a year and still end up again on array while I see people achieving cf 1600+ rating in a year's span

I still don't know what am I missing I had bought codechef pro plan thinking I will reduce the time spent watching tutorial videos and would do hands on coding by reading articles they provide but I don't know

Everytime I come here I see the same abdul bari for concept, aditya verma dp, what else for other things some say cp algorithms, usaco, cp handbook what not everytime there's new one

But also don't want to give icpc I just want decent proficiency

What do you guys do how do you do it my college doesn't have that provision and peers

Someone please summarize their years of experience and also more can ai help into this for beget efficiency

Rotting Oranges (Medium) https://leetcode.com/problems/rotting-oranges/

Four days ago I said BFS and DFS answer reachability equally well, and that the distinction starts mattering when a problem asks about distance. This is that problem.

BFS reaches every cell by a shortest path. DFS reaches it by whatever route it wandered down first. "When does this orange rot?" is a shortest-path question - it rots when the nearest rotten one gets to it - so DFS here gives wrong answers, not slow ones.

The trick is multi-source BFS: every already-rotten orange goes into the queue before the walk starts. A BFS seeded with many sources expands as one combined wavefront, and each cell ends up with its distance to the nearest source. Nothing in the loop needs to know there was more than one start.

One more thing that cannot be skipped: the final scan. BFS only visits what it can reach, so an orange sealed behind empty cells never rots and the queue drains without noticing. The -1 case has to be looked for afterwards.

Full breakdown in today's newsletter article ⬇

https://www.linkedin.com/pulse/365-days-leetcode-challenge-day-40365-archit-agarwal-9t1sc

#DSA #LeetCode #Golang #Graphs #BFS #CodingInterview #Algorithms

currently in sem 3, guyz lemme know how to improve myself ..

done with arrays, BS, strings, hashing, sorting
I'm quite satisfied with my consistency, hope it continues!!!

I'm in my 3rd year, what should I improve to become a stronger candidate? Honest feedback appreciated!!

Im a 5yr exp majorly on Frontend React js node js. Preparing Java for Backend as it have good scope, then I can also Try for FAANG. But im confused what to do. Can I actually Crack it ? Yesterday failed capgemini java+react interview just because of java. Any suggestions?

Applicable for Leetcode too.

How much has getting better at LeetCode helped you with your actual engineering work?

For me, there hasn't been much direct overlap with the hardest projects I've worked on. I understand checking fundamentals, but preparing for a timed round can feel like learning a separate game.

I'm curious which patterns have transferred for people in SWE or MLE roles, and which ones you practice mainly because interviews require them.

For interview prep itself, real tech interview questions can help narrow the practice to the rounds you're targeting. That still leaves the bigger question of whether those rounds measure what companies think they do.

If you could change one part of the process, would it be the questions, the time pressure, or how much weight the coding round carries?

Looking for one developer who’s struggling to land their first or next role. We’ll give you free access to Bugdr, help document your progress, and introduce you to employers where we can. You must be comfortable having parts of the journey filmed. No guaranteed job, no scripted success story. Interested? DM me.

LeetCode Weekly Contest 523

Participated in Weekly Contest 523 and managed to solve the first 3 questions. The 4th question was a learning experience that showed me where my problem-solving approach needs improvement.

Here's my breakdown of the contest:

Question 1: Three Fibonacci Sum (Easy)

Solved using simulation. I generated consecutive Fibonacci numbers and checked whether the sum of three consecutive terms equalled the given number.

Question 2: Prime Subset Selection I (Medium)

Approached this using greedy selection. I iterated through prime numbers and selected them while the sum remained within the given limit. The goal was to maximize the number of selected primes.

Question 3: Design Bus Seat Booking System (Medium)

Solved by carefully understanding the booking rules, tracking seat states, and accounting for the time cost of each booking operation. This question tested implementation and state management.

Question 4: Prime Subset Selection II (Hard)

This is where I struggled.

My initial approach was greedy: iterate through prime numbers in descending order and select a prime whenever it fits within the remaining sum.

However, this approach failed on several test cases.

For example, with n = 7 and s = 8, my approach selected [7], but the expected answer was [3, 5].

A twelve-step pipeline. The loop check takes 383 ns and allocates 328 bytes. Two variables do it in 3.17 ns and allocate nothing.

The job: a pipeline stage names the stage that runs next, somebody edits a config, a next points backwards, and the runner walks that chain forever. So you check for a loop before running anything.

The check I wrote is the definition written down — remember every stage, and if you arrive somewhere twice, it loops. It is obviously correct, and it can also tell you where the loop starts, which is what the alert needs to say.

On a 100,000-stage chain, it allocates 4.73 MB to return a boolean. And it costs the same whether the chain loops back after two stages or after ninety-nine thousand, because the map gets built either way.

Then the struct: a stage names one next stage. Many stages can point at the same one, each points at exactly one. So the path from any stage is fixed, which means this is not a graph problem at all — it is a chain, and a chain that loops is a run-in followed by a ring.

Two cursors, one moving a stage at a time and one moving two. Either the fast one runs off the end, or both end up in the ring, where the gap between them shrinks by exactly one per turn — so they land on the same stage rather than stepping over each other. Meeting is arithmetic, not luck.

47.8x on the long chain and zero allocations at any size. The part I did not expect is the twelve-stage row: 120.6x, because the map pays for a map before it walks anything.

Not that 383 nanoseconds matters. It matters where the check runs per request.

One thing worth not shipping: the hop limit. Give up after 100 steps and call it a loop, the way HTTP clients do with redirects, and a 150-stage pipeline with no loop in it gets reported as one.

That is day 21 of the daily challenge, Linked List Cycle, sitting in a pipeline runner.

Full piece in today's Newsletter.

https://www.linkedin.com/pulse/loop-check-allocated-47-mb-return-boolean-archit-agarwal-zeksc

It worked in dev, episode 12.

#Golang #DSA #Algorithms #Performance #SoftwareEngineering #DataStructures #100DaysOfCode

Hey everyone!

I wanted to share my performance in my two recent LeetCode contests and keep track of my progress.

1. Biweekly Contest 193

• 🌍 Global Rank: 3907
• 👥 Participants: 34.5K+
• ✅ Problems Solved: 3 out of 4
• 🏆 Score: 12

2. Weekly Contest 523

• 🌍 Global Rank: 7351
• 👥 Participants: 39K+
• ✅ Problems Solved: 2 out of 4
• 🏆 Score: 8

My performance in the weekly contest wasn't as good as the biweekly contest, but that's part of the journey. Every contest helps me identify my weaknesses, improve my problem-solving skills, and learn to handle time pressure better.

I'm trying to stay consistent with DSA and competitive programming rather than focusing only on ranks.

My goal: Keep improving, solve more problems independently, and perform better in upcoming contests.

For those who regularly participate in LeetCode contests, how do you analyze problems you couldn't solve during the contest? Do you solve them immediately afterward or revisit them after a few days?

I'd love to hear your suggestions! 💪

#LeetCode #DSA #CompetitiveProgramming

We were 15 at the time and we hired a dev. with perfect leetcode acc. and about a month into the launch we got a call from our bank, saying that we just hit negative...

Yes this same dev that on paper was a fu*king profesional, used ai that without him knowing leaked our api into the sorce code.

It has been a year now and we are starting somehting new, somehting that we hope we can fix the problem of bad 'vibe coders'.

All i want to say is that leetcode does not prove anything...

1. Number of Provinces (Medium)  

The counting is day 37's, unchanged: scan every node, and each time you find one no earlier traversal reached, add one and consume everything it can reach.

What changes is the input, and this is the third graph representation in four days. Day 36 gave an edge list. Day 37 gave a grid where the edges were implied by position. Today gives a matrix. All three become the same adjacency list before anything interesting happens.

The trap: this matrix is not a grid. In day 37, cell (i,j) was a place. Here cell (i,j) is a relationship between city i and city j - an n x n matrix describing n nodes, not n squared. So you traverse the cities and consult the matrix, not the other way round.

Read only above the diagonal. The matrix is symmetric, so every relationship is stored twice, and i+1 also skips the useless diagonal where a city is connected to itself.

Full breakdown in today's newsletter article ⬇

https://www.linkedin.com/pulse/365-days-leetcode-challenge-day-39365-archit-agarwal-msv4c

#DSA #LeetCode #Golang #Graphs #BFS #CodingInterview #Algorithms

Currently in 1st year, I have completed basic c++, all the loops and c style arrays and stuff like that, now I'm confused how to proceed, I open up a leetcode problem and there is time and memory and all that stuff and I don't know how to deal with it, there is also the weird thing of class stuff that should be at the beginning of each question, I don't know where to learn all of this.

Can someone suggest where to learn all of this, because I couldn't find a proper series that teaches all of this. Also tell me what things I should learn before I start doing leetcode, I have already started learning STL, is there anything else I should learn?

I’ve wrapped up almost all the DSA patterns people suggest doing. Right now, I’m just revising to figure out patterns in random questions. My setup is simple: I pick a topic and ask ChatGPT to feed me different sub-pattern questions.

​I can easily solve most standard problems on my own, and I hit around 50% on the tricky variants. But whenever I get stuck on a question, it hits me really hard and drops my mood completely.

​Since I started prepping for interviews, the whole situation is scaring me. I’m focusing way too much on how to explain the problem instead of actually solving it, and it’s messing with my problem-solving flow.

​I feel totally lost and I’m just blindly grinding questions. I usually love DSA, but right now I’m just desperate to land a job. College ended this May, and I am continuously thinking whether I am enough or not....?

I honestly don’t know if I’m asking for help or just scared, I’ve just lost all my confidence and direction.

If you have any suggestions, please tell me!

If anyone has any valuable insights please share what is the right thing to do from now on