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Difficulty: MEDIUM
Problem: Lowest Common Ancestor of a Binary Tree

Problem gist

Given the root of a binary tree and two existing nodes p and q, return their lowest common ancestor.

An ancestor can be the node itself. That detail matters: if p is above q, then p is the answer. “Lowest” means deepest in the tree, not smallest by value. This is a normal binary tree, so there is no useful ordering rule like there would be in a binary search tree.

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What happened

Microsoft Research’s official research blog published Red-teaming a network of agents: Understanding what breaks when AI agents interact at scale, a post arguing that many agent risks only become visible when agents interact with each other as a network.

The core claim is that an agent can look acceptable in isolation and still behave badly once it becomes part of a shared environment. Microsoft tested this on a live internal platform with more than 100 always-on agents, each linked to a human principal. The agents used different models, including GPT-4o, GPT-4.1, and GPT-5-class variants, and interacted through forums, direct messages, scheduling tools, currency exchange, a marketplace, and a reputation system.

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A Long Deadline with No Easy Fix

Phil Plait’s column begins with the sun as the most ordinary fact in human experience: it lights and warms Earth, and life has spent billions of years adapting to it. The twist is that the sun is not a permanent background condition. It is a star with a life cycle, and its slow internal changes will eventually make Earth uninhabitable even without any asteroid, nearby supernova or human-made disaster.

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Selected problem: URL Shortener Analytics

Scope: Design the analytics subsystem for a URL shortener: capture click events, compute useful aggregates, and serve owner dashboards without slowing down redirects.

Source grounding: Grokking frames analytics as an extended URL shortener requirement and calls out the danger of updating a shared counter row on every popular redirect; Alex Xu highlights that redirect choice affects analytics fidelity; DDIA supplies the storage and processing lens for event logs, OLTP versus OLAP separation, materialized aggregates, stream windows, partitioning, replication, and idempotent recovery.

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What happened

Techmeme surfaced this May 3, 2026 item in its Techmeme cluster, and the direct source used here is NIST’s May 1, 2026 CAISI Evaluation of DeepSeek V4 Pro.

The Center for AI Standards and Innovation evaluated DeepSeek V4 Pro, DeepSeek’s latest open-weight model, across cyber, software engineering, natural science, abstract reasoning, and math tasks. CAISI’s headline finding is deliberately two-sided: DeepSeek V4 Pro is the most capable Chinese model the group has evaluated so far, but it still appears to trail the leading US frontier models by about eight months in aggregate capability.

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This summary covers The Economist’s April 11th, 2026 Business column listed in the section contents as Bartleby: Stretch goals and published under the headline Stretch or routine?.

The column asks when very hard targets help an organisation break out of stale habits, and when they simply push people into reckless behaviour. Its answer is deliberately balanced: stretch goals can be powerful, but they are not a management magic trick. They work best when they force useful reinvention, not when they turn pressure into denial.

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James Bradley’s Winter 2026 Association column starts with the kind of memory that makes free flight feel irreplaceable: a strong, smooth coastal wind, a forgiving dune, a small speedwing, and a flight that stayed vivid after a thousand others. The point of the story is not nostalgia. The site where that memorable day happened was later lost after a multi-year lawsuit by a neighboring homeowner, and Bradley uses the loss to warn pilots that access can disappear through ordinary failures of judgment as much as through dramatic accidents.

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US gas prices reaching new heights as war in Iran drags on (r/news)

• Affectionate_Tip_934: Gas prices don’t just hurt at the pump. Every product that gets trucked, shipped, or flown becomes more expensive within weeks. This isn’t just a fuel story, it’s a silent tax on everything you buy for the next 6 months.
• The_Frozen_Inferno: US gas prices? You mean WORLD gas prices. A lot of us that have absolutely nothing to do with this BS war are going to suffer as well.

Court restricts abortion access across the US by blocking the mailing of mifepristone (r/news)

• Mediocre_Ad_4649: I thought nationwide injunctions can’t be issued anymore? So wouldn’t this “only” apply to the fifth district?
• Grant_Winner_Extra: The 5th circuit is the most-overturned circuit and they’ve tried this a half dozen times already. It will get overturned and even if it doesn’t, it only applies in the 5th circuit.

Trump says he will raise tariffs on EU autos to 25% (r/worldnews)

• Qrimesz: Honey, it’s friday again!
• tri170391: He seems to forgot the supreme court ruled his tariff illegal lol.

Louisiana Republicans eliminate elected position days before an exoneree was set to take office (r/nottheonion)

• braumbles: Not shocking. This is what Republicans do.
• ComprehensiveHavoc: A good man’s redemption scared them so much that they needed to find a new way to be corrupt.

US birth rates just hit another record low, what do you think is the leading cause of this? (r/AskReddit)

• LunaraVibe: It turns out that when ‘starter homes’ cost half a million dollars and childcare is basically a second rent payment, people start treating having a kid like a luxury hobby they can’t afford.
• AvleeWhee: gestures vaguely at everything

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Amazon INTENSIONALLY leaks layoffs (Blind)

• nthin2lose (SentinelOne): Amazon knows how to keep everything toxic.
• Jefry (Salesforce): They also stack rank by spelling performance.

Mass Layoffs Have Consequences (Blind)

• RowdySWE (Block): Elon basically gave CEOs permission to start doing this when he ripped apart twitter and it was still functioning.
• crazzak (Microsoft): Employees don’t feel invested in companies that throw them away like trash the second it saves them a buck; this leads to less innovation and decline in quality.

Congratulations Google (Blind)

• HypeOS (Apple): Pretty sure this revenue is a bit of a faff. GCP is charging Gemini and recording this as revenue for serving Google Gemini responses?
• Zuckerbrug (Samsung): Listen to the earnings call. Not only cloud but they are owning AI. OpenAI better get that IPO done soon before Google eats their lunch…

Meta contractor fires 1,100 AI trainers after they revealed Ray-Ban glasses recorded private and intimate footage (r/technology)

• CanvasFanatic: Note that some of these contractors came forward to blow the whistle on what they were being asked to do (despite how little they were being paid) and were punished for it.
• bigkoi: The glasses with camera thing is creeping. It’s the modern equivalent of the guy wearing mirrors on his shoes.

Palantir Workers Are Finally Noticing The Skulls On Their Caps (r/technology)

• BeMancini: “Okay, how about we plant a story in the media that you all feel really really bad about it? Will that get you to stay until your stock is vested? Will that get you to stay until we unceremoniously lay you off?”
• zhaoz: “It is difficult to get a man to understand something when his salary depends upon his not understanding it”. Upton Sinclair.

Sam Altman No Longer Believes In Universal Basic Income (r/singularity)

• Lankonk: I mean, he’s not wrong. UBI would be insufficient if 20 people owned everything. A broader, collective ownership of the world’s enterprises would go a long way towards preventing a catastrophic concentration of power.
• revengeofwalrus: He’s a narcissistic sociopath. Of course he’s changing his tune.

Why does it feel like tech has no middle ground at all? (r/cscareerquestions)

• Bulbasaur2015: interview process is harder than the job
• Loupreme: You’re in a reddit bubble, people are getting paid in all ranges. However I will say 80-110k for a senior would be robbery (in the US at least) so not sure what middle ground you’re thinking of, for non seniors sure those exist too

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What happened

Cloudflare’s official engineering blog published Introducing Dynamic Workflows: durable execution that follows the tenant, a post about making durable workflow execution work when the workflow code is not known at deploy time.

The problem is a real platform boundary. Cloudflare Workflows already gives developers a durable execution engine: a workflow can survive process eviction, sleep for long periods, wait for external events, retry individual steps, and resume after failures. That model works cleanly when the workflow class is part of the platform owner’s deployment. It breaks down for modern multi-tenant products where every customer, repository, agent, or session may bring different code.