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Quick facts

• Difficulty: MEDIUM
• Problem: Perfect Squares
• Topics: Math, Dynamic Programming, Breadth-First Search

Problem gist

Given a positive integer n, the task is to return the fewest perfect square numbers whose sum is exactly n. A perfect square is a number such as 1, 4, 9, 16, and so on.

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Quick facts

• Difficulty: MEDIUM
• Problem: Range Sum Query 2D - Immutable
• Topics: Array, Design, Matrix, Prefix Sum

Problem gist

The class receives a fixed 2D matrix and must answer many rectangle-sum queries. Each query gives the top-left cell (row1, col1) and the bottom-right cell (row2, col2), and asks for the sum of every matrix value inside that inclusive rectangle.

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Quick facts

• Difficulty: MEDIUM
• Problem: Time Based Key-Value Store
• Topics: Hash Table, String, Binary Search, Design

Problem gist

Design a key-value store that remembers history. A normal hash map answers “what is the current value for this key?” This problem asks “what was the value for this key at this timestamp?”

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The Moon’s origin story gets a sharper fingerprint

The article revisits one of planetary science’s most famous creation stories: the Moon likely formed after a Mars-size body, usually called Theia, slammed into the young Earth. That giant impact melted large parts of Earth, destroyed Theia and threw enough debris into orbit for the Moon to assemble from the wreckage.

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What happened

Techmeme surfaced Emma Roth’s May 12, 2026 article for The Verge, and the original article is George Clooney, Tom Hanks, and Meryl Streep back new ‘Human Consent Standard’ for AI licensing. The Techmeme item framed the announcement as a new AI licensing effort from RSL Media, backed by high-profile creative figures and entertainment organizations.

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This summary covers The Economist’s April 25th, 2026 International article listed in the contents as European defence tech and published under the headline Slow and unsteady.

The article argues that Europe has begun to understand the military importance of cheap, software-driven unmanned systems, but has not yet built the industrial machinery needed to produce them at wartime scale. Drones, autonomous submarines, unmanned ground vehicles and battlefield software are no longer speculative extras. They are becoming central to how modern armies detect, strike, supply and survive.

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Black Hills drilling project canceled after backlash from tribes (r/news)

• rieirieri: Such a welcome reprieve from all the depressing headlines. Good on the tribes for fighting this. I’m so glad they won.
• get__jinxxed: HELL YEAH! Great job to the tribes!
• Lazy-Impress-9708: Great news. Need some wins like this up in Alaska.

6 people found dead inside cargo train boxcar in Texas (r/news)

• YcemeteryTreeY: Sadly it was probably human smuggling. Smugglers dont care, they will abandon everyone if they think theyre going to get caught.
• lormightymike: Reminds me of the beginning of Season 2 of the Wire when they found 13 dead women in the shipping container.
• thatgirl25_: How strange and tragic is the reality that we currently. That people need to risk their lives and flee to other lands to feel safer. And the only thing separating us from this horrific ending is geographical luck. First world nations existing on the exploitation of the second and third world will not last.

Fugitive former Polish Justice Minister Zbigniew Ziobro is now in the United States courtesy of a visa from President Donald Trump after fleeing Hungary (r/worldnews)

• pixtax: “i have the best people.”
• ButterscotchOk5339: Welcomed by both Orban and Trump? Sounds guilty to me.
• gianluca_antonelli: He doesn’t want immigrants because they would increse the criminality, then proceeds to host criminals in his country👍

Vatican recognises the ‘pain’ experienced by LGBTQ+ Catholics in landmark report (r/worldnews)

• urbanek2525: The Pope tried to condemn the practice of slavery in the US too. I guess he’s going to find out that most Catholics listen to him only when he tells them what they want to hear.
• Cultural_Meeting_240: only took them like 2000 years to figure that one out.
• Miss-Information_: Ooooo just in time for politics Monday in the Catholicism sub

TIL that the oldest active organization affiliated with New Orleans Mardi Gras hasn’t marched in the parade since 1991 because it refuses to let non-white people join. (r/todayilearned)

• ComprehensiveForm129: Each step of the way, I couldn’t have predicted where that sentence was going
• puddinfellah: To be clear, the ordinance was struck down in 2000 for privacy concerns, but unlike the other krews, it did not return to the parade.
• Klockworth: So it’s a white Anglo-Saxon Protestant crewe that didn’t allow Catholics marching in a parade celebrating a catholic holiday?

What’s a “rich people thing” you experienced once and immediately understood why rich people love it? (r/AskReddit)

• AfterHoursAllure: A first class lie flat seat on a long haul flight. I showed up tired, ate real food with a metal fork, put on pajamas, and slept horizontally at 35,000 feet. Got off the plane like a human being. No neck pain, no regret. Suddenly understood why people never go back
• Concave007: tailored clothing. wore a shirt that actually fit once. spent the next 10 years angry at every shirt i’d ever owned.
• ZebraMussell: I used to think rich people were impatient because they were entitled. I realized they’re “impatient” because they’ve tasted what it’s like when the world actually works efficiently, and once you’ve had that, every 15 minute delay feels like a personal tax on your life.

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Is Java a looked down upon language, if you code in Java you a disgrace? (Blind)

• Satya N. 🧑🏽‍🦲 (Microsoft): Yes it signals WITCH tier. And whatever you do don’t say spring boot lmfao
• bjdpq (Microsoft): To the people saying it’s looked down upon, what is the elite language?
• AI (Stripe): Who still cares about language now? We have AI.

Is Microsoft still a decent place to work for? (Blind)

• WhoAmI000 (Microsoft): Remember you’re on Blind where default mode is grumpy with victim mentality. Of course you’re going to hear it sucks. This isn’t where the happy people hang out. Truth is, it’s like every other enterprise - depends on the group, your work and manager. There are people who are very good who love their jobs at Microsoft - just like everywhere else. However, the majority aren’t here lurking Blind.
• nutella_x (Atlassian): Microsoft gave me chronic anxiety that i’m still dealing with years later. It was downright traumatizing.
• AIBotFarm (Microsoft): If you like being gaslit, it’s a great place to work.

Get out while you have the chance (Blind)

• IAmBethG (Amazon): Getting fired for slacking is actually way harder than you think. I’ve been slacking for twice as long as the severance would have been if I got lucky at the beginning.
• byemsft🤣 (Microsoft): Yes. I had a bad altercation with my manager yesterday and I will be leaving soon
• nohana4u (Salesforce): Mental health impacts general health at some point. I know first hand and wished I would have someone pushing this advice to me.

AI data centers face increasing complaints about inaudible but ‘felt’ infrasound — citizens complain high- and low-frequency sounds do not register on decibel meters but cause adverse health effects (r/technology)

• Sherman140824: Vibrations disrupt sleep
• winterbird: But the rich don’t want to hear emergency transport helicopters landing at a children’s hospital sometimes.
• 6gv5: If there are infrasound involved, seismometers must be able to detect them.

Louis Rossmann tells 3D printer maker Bambu Lab to “Go (Bleep) yourself” over its threatened lawsuit against enthusiast — Right to Repair advocate offers to pay the legal fees for a threatened OrcaSlicer developer (r/technology)

• kilgoreq: I’m always on Rossmann’s side.
• Cyrisaurus: Pro-tip for companies that want to look consumer friendly: don’t threaten the guy who has dedicated his life to fighting for customer rights
• paulerxx: Louis Rossmann is a legend and every single one of us should be on his side.

How much will you miss traditional programming? (r/cscareerquestions)

• RegretNo6554: i kinda miss it but i’m just glad i went thru the struggles of learning programming from scratch pre AI and running into so many walls that trained up my debugging skills. nowadays im just building shi really fast with AI that i never had the time to do. I’ve been solving more of my own problems now rather than business or arbitrary homework problems.
• disposepriority: I still do a lot of traditional programming, because without setting up the general structure, expectations, interactions and abstractions AI takes a piss all over my codebase, so I’m not sure what you’re on about.
• andrasta25: We’re automating out the fun part. Some folks are talking about making skills that will take jira tickets and write the code for us. If we become professional jira ticket writers that’s not what I signed up for.

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What happened

Anthropic’s official research blog published Natural Language Autoencoders: Turning Claude’s thoughts into text, a post about converting internal model activations into readable explanations that can support safety audits, debugging, and interpretability research.

The problem is that language models expose words at the interface but operate internally on dense activation vectors. Those activations may carry information about what a model is tracking, planning, or concealing, but they are not directly legible. Existing interpretability tools such as sparse autoencoders and attribution graphs can reveal structure, but they still leave researchers with complex artifacts that require expert interpretation. Anthropic’s natural language autoencoders, or NLAs, try to make that hidden state speak in ordinary text.

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Difficulty: MEDIUM
Problem: Binary Tree Zigzag Level Order Traversal

Problem gist

The input is the root of a binary tree. The task is to return the node values level by level, but the direction alternates:

• The root level is read from left to right.
• The next level is read from right to left.
• The next level flips back to left to right, and so on.

For example, a tree with levels [3], [9, 20], and [15, 7] should return three rows: [3], then [20, 9], then [15, 7].