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A backcountry project built from a mining ruin

Heather Hansman’s “Searching for Gold” begins with a useful reversal. The North London Mill near Colorado’s Mosquito Pass once existed to extract literal wealth from the mountains, sending silver and gold out into the world before collapsing into the usual tangle of incompetence, mismanagement and rot. Now people are coming back to the same basin in search of something far less tangible: spring ski lines, a sense of history and a more communal way of using the backcountry. That shift gives the article its core idea. This is not just a story about a hut. It is a story about what happens when a place built for extraction gets reimagined as a place for stewardship.

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Quick facts

• Difficulty: MEDIUM
• Problem: Longest Consecutive Sequence
• Main tags: Array, Hash Table, Union-Find

What the problem is really asking

The input is an unsorted integer array. The task is to find the length of the longest run of values that can be arranged as x, x + 1, x + 2, ....

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Quick facts

• Difficulty: MEDIUM
• Problem: 3Sum
• Main tags: Array, Two Pointers, Sorting

What the problem is really asking

The input is an integer array, and the goal is to return every unique triplet whose values add up to 0.

Two details make the problem harder than it looks:

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Quick facts

• Difficulty: MEDIUM
• Problem: Next Permutation
• Main tags: Array, Two Pointers

What the problem is really asking

The array represents one permutation of the numbers.

The task is to mutate it into the very next permutation in lexicographic order, which means:

• make the number just a little larger
• keep that increase as small as possible
• do everything in place

If the current permutation is already the largest possible one, such as [3, 2, 1], then there is no larger answer. In that case, the correct result is the smallest permutation, which is ascending order.

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Quick facts

• Difficulty: MEDIUM
• Problem: Decode String
• Main tags: String, Stack, Recursion

What the problem is really asking

The input is an encoded string where patterns like 3[ab] mean “repeat ab three times.” The tricky part is that the repeated part can itself contain more encoded pieces, such as 3[a2[c]].

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Quick facts

• Difficulty: MEDIUM
• Problem: Maximum Subarray
• Main tags: Array, Divide and Conquer, Dynamic Programming

What the problem is really asking

The input is an integer array, and the task is to choose one contiguous subarray whose sum is as large as possible.

The important constraint is contiguity. This is not “pick the best numbers anywhere in the array.” Once a starting point is chosen, the subarray must be one uninterrupted block.

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Quick facts

• Difficulty: MEDIUM
• Problem: Merge Intervals
• Main tags: Array, Sorting

What the problem is really asking

The input is a list of inclusive intervals like [start, end]. The goal is to combine every set of overlapping intervals and return the smallest list of non-overlapping intervals that covers the same ranges.

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Quick facts

• Difficulty: MEDIUM
• Problem: Reverse Integer
• Main tags: Math

What the problem is really asking

Given a signed 32-bit integer, reverse its decimal digits.

Examples:

• 123 becomes 321
• -123 becomes -321
• 120 becomes 21

The catch is that the answer must still fit inside the signed 32-bit range:

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A mission that is halfway to its real goal

Jonathan O’Callaghan’s article is not mainly about the Perseverance rover itself. It is about the awkward possibility that NASA may complete the expensive, glamorous first half of a historic Mars experiment and then abandon the second half before the science can pay off.

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What happened

Techmeme surfaced this story in its April 11, 2026 roundup, and the original report is Uncovering Webloc: An Analysis of Penlink’s Ad-based Geolocation Surveillance Tech.

Citizen Lab’s report describes Webloc as a commercial surveillance system built from ordinary advertising and app exhaust rather than a classic zero-click exploit or telecom intercept. The researchers say the platform, developed by Cobwebs Technologies and now sold by Penlink, gives customers access to a constantly refreshed feed of location records tied to as many as 500 million mobile devices worldwide. In practical terms, that means governments can reconstruct where people live, travel, work, worship, protest, or seek medical care by buying data that originally entered the market through mobile apps and ad-tech pipelines.