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HARDArray, Stack, Monotonic StackEach bar in the histogram has width 1, and the goal is to find the largest
possible rectangle that can be formed by taking one or more adjacent bars.
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MEDIUMHash Table, Linked List, Design, Doubly-Linked ListThis problem is not mainly about storing key-value pairs. It is about building a data structure that can answer two different questions at the same time:
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MEDIUMArray, Binary SearchThis problem does not ask for the maximum value in the whole array.
It only asks for any index whose value is greater than its neighbors. That is a much weaker requirement, and that weaker requirement is exactly what makes the binary-search solution possible.
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MEDIUMArray, Prefix SumFor each index, the answer should be the product of every number except the one currently sitting at that index.
If the input is [1, 2, 3, 4], then:
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MEDIUMHash Table, String, Sliding WindowThe input is a string and a budget k. One operation lets us replace any
single character with any other character. The goal is to find the longest
substring that can be turned into a string of all one repeated character using
at most k replacements.
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This article traces a recurring pattern in the search for life beyond Earth: confidence rises when a new discovery makes alien life seem plausible, then falls when better evidence strips away an attractive illusion. The central argument is not that scientists are close to proving the existence of intelligent extraterrestrials. It is that the case for life elsewhere has become stronger in a different and more modest way than many people once imagined.
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Selected problem: TinyURL
Scope: Design a highly available URL shortening service that creates compact aliases, resolves them with very low latency, and records click analytics without putting the redirect path at risk.
Also see https://wiki.derricklin.net/software-development/System%20Design%20Interview/#url-shortener
This is the classic URL shortener problem: map a short code to a long URL, make redirects fast, and survive a very read-heavy workload with occasional viral hot keys.
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Techmeme surfaced this story on its April 22, 2026 page, and the original article is TechCrunch’s SpaceX is working with Cursor and has an option to buy the startup for $60B.
At the center of the story is a deal that is much bigger than a normal infrastructure partnership. TechCrunch reports that SpaceX told investors it is working with Cursor on a next-generation coding and knowledge-work AI effort, and that the agreement gives SpaceX a choice later this year: either pay Cursor $10 billion for the partnership or acquire the company for $60 billion. Even in a market that has become numb to giant AI numbers, that structure is startling. It treats the collaboration itself as enormously valuable while also creating a path to full vertical integration if the training work goes well enough.
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This summary covers The Economist’s April 11th, 2026 Science & technology article listed in the contents as Curing all diseases with AI and published under the headline Panacea seer.
The article is built around a large claim: that artificial intelligence may eventually become a general-purpose engine for inventing new medicines, rather than just a tool for speeding up narrow research tasks. The immediate focus is Demis Hassabis, the head of Google DeepMind, and his spin-off company Isomorphic Labs. The broader point is that AI drug discovery is moving from promise and publicity towards something more concrete: actual candidate drugs that can be tested in the real world.
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Jugdeep Aggarwal’s article is nominally a season recap of the Northern California Cross Country and Sprint Leagues, but its real subject is a smarter way to bring more pilots into cross-country flying. The league runs one race-to-goal weekend per month from March through October at Bay Area and Sierra-adjacent sites, yet it is deliberately framed less like a hard-edged competition circuit and more like a structured group adventure. Pilots get tasks, briefings, and the motivational pull of a goal, but they also get friends to fly with, organized retrieves, and a culture that welcomes people who are curious about XC without already identifying as racers.
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