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HARDArray, Binary Search, Divide and ConquerTwo arrays are already sorted. If they were merged into one larger sorted array, the task would be to return the middle value.
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HARDArray, Two Pointers, Dynamic Programming, StackThe input is an elevation map where each number is the height of a vertical bar with width 1.
After rain falls, water can sit in the valleys between taller bars. The task is to compute the total amount of water that stays trapped.
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MEDIUMArray, Two Pointers, GreedyThe input is an array of heights. Each height represents a vertical line drawn at that index.
The task is to pick two lines that, together with the x-axis, form a container that holds the most water.
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MEDIUMLinked List, Math, RecursionTwo linked lists represent two non-negative integers. Each node stores one digit, and the digits are already in reverse order, so the ones place comes first.
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MEDIUMHash Table, String, Sliding WindowGiven a string, the goal is to find the length of the longest contiguous block of characters with no repeats.
The important word is contiguous. This is not asking for a subsequence that can skip characters. It is asking for one unbroken window inside the string.
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MEDIUM64.1Two Pointers, String, Dynamic ProgrammingGiven a string, return the longest contiguous substring that reads the same forward and backward.
The word “substring” is the important constraint. This is not about picking scattered characters. The answer has to be one continuous block inside the original string.
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MEDIUMArray, Hash Table, Prefix SumThe input is an integer array and a target k.
The task is not to find the longest subarray or to return the subarray itself. It is simply to count how many contiguous subarrays add up to k.
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This article is about a change in how astronomers see the universe.
For a long time, space was often described as majestic but slow. Galaxies evolved over billions of years, stars lived and died over immense stretches of time, and most cosmic change seemed far removed from ordinary human experience. Ann Finkbeiner argues that this picture is now incomplete. Modern surveys are revealing a universe full of sudden, violent, short-lived events called transients: flashes that can appear without warning, blaze with absurd amounts of energy, and then fade on timescales of seconds, days or months.
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This summary covers The Economist’s March 28th, 2026 Science & technology article listed in the contents as NASA's updated Moon-base plans and headlined on the page as Back to stay.
The article argues that NASA is trying to turn its Moon programme from an awkward, overcomplicated prestige project into something more durable. Instead of treating the next crewed landing as the main event, the agency now wants that landing to be the start of a longer campaign: repeated visits, more equipment on the surface and eventually a real base.
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Eric Engerbretson’s piece reads like a farewell to a beloved hang gliding landmark, but its real subject is infrastructure. Wallaby Ranch was not just a nice place to fly. It was a carefully built system for introducing people to hang gliding safely, repeatedly, and with enough comfort and joy that many of them stayed in the sport.
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