Bitcoin price on September 16, 2026: BTC closed at $76,144.99, up 0.74%, after a low of $74,911.53 that stopped $24.03 above Tuesday’s low and a Federal Reserve rate hike — the first since 2023 — landed inside the same UTC day. The snapshot and charts are first, the short version follows, and the full explanations are at the end for anyone who wants them. Informational only. This brief reports market data and publicly available news. It is not investment, trading, or financial advice, and it does not recommend buying, selling, or holding anything. The author is not responsible for any READ MORE
Bitcoin Daily Brief — September 15, 2026: BTC Falls 3.3% to $75,584 as the CLARITY Act Fails in the Senate; Close Lands $96 Above the Lower Band
Bitcoin price on September 15, 2026: BTC closed at $75,584, down 3.31%, in a $3,355 range between a $78,243 high and a $74,888 low — the largest single-day decline since June 5, on the heaviest volume since September 3, on an afternoon when the Senate’s CLARITY Act cloture vote failed and the close finished $96 above the lower Bollinger Band with the Federal Reserve’s decision one session away. The snapshot and charts are first, the short version follows, and the full explanations are at the end for anyone who wants them. Informational only. This brief reports market data and publicly READ MORE
Bitcoin Daily Brief — September 14, 2026: BTC Rebounds 1.8% to $78,175; $80,000 High Rejected, MACD Narrows First Time in 11 Days
Bitcoin price on September 14, 2026: BTC closed at $78,175, up 1.79%, in a $3,244 range between a $79,591 high and a $76,347 low — a Monday rebound that recovered $1,375, cut the shortfall to the 20-day average from $1,679 to $286, and produced the first narrowing of the MACD histogram in eleven sessions, with the Federal Reserve’s decision now two sessions away. The snapshot and charts are first, the short version follows, and the full explanations are at the end for anyone who wants them. Informational only. This brief reports market data and publicly available news. It is not READ MORE
Bitcoin Daily Brief — September 13, 2026: A Quiet Sunday Sheds $463 as the Golden-Cross Gap Clears $1,000
Bitcoin price on September 13, 2026: BTC closed at $76,800, down 0.60%, in a $968 range between a $77,425 high and a $76,457 low — a quiet Sunday that nonetheless gave back $463, took the close to a fifth consecutive session beneath the 20-day average and trimmed the cushion above the 200-day average by $507, with the Federal Reserve’s decision now three sessions away. The snapshot and charts are first, the short version follows, and the full explanations are at the end for anyone who wants them. Informational only. This brief reports market data and publicly available news. It is READ MORE
After the Sort: Partition and Two Pointers in C++
Sorting an array to answer a question about it is often the wrong move, and this post is about the two ways to notice. The first: sometimes you do not need the array sorted, only partly sorted. Quicksort’s partition step puts one element in its final place and separates everything else into two sides — and if all you want is the k-th largest, that single step is enough, and repeating it is O(n) rather than O(n log n). Four problems below are that idea. The second: sometimes you do want it sorted, and then sorted order pays you back READ MORE
Interval Problems in C++: One Sort, One Sweep, and a Heap When You Need It
Interval problems look like a family of tricks. They are one trick applied seven ways, and the trick fits in a sentence: sort by start time, and every question about overlap becomes a question about the element you just looked at. Without the sort, “do any two of these overlap?” is a pairwise check over n² pairs. With it, an interval can only overlap the ones immediately around it, so one linear walk answers the question. Three of the seven problems below need nothing more than that walk. The other four need one extra structure — a heap — and READ MORE
Sorting in C++: Five Algorithms, Stability, and What the Merge Step Buys You
Almost nobody implements a sorting algorithm at work. You call std::sort and move on. So the usual defence of learning them — “it builds fundamentals” — is doing a lot of unpaid labour in that sentence. Here is a better reason, and it is the one this post is built on. Three of the five algorithms below contain a reusable subroutine that shows up as LeetCode problems in its own right. Merge sort’s merge step is a problem. Quicksort’s partition step is four problems. And one character inside merge sort decides whether the algorithm is stable, which changes what you READ MORE
Binary Search on the Answer in C++: Five Problems With Nothing to Search
Nobody stores an array of eating speeds. There is no sorted list of ship capacities. And yet both problems are binary search, and recognising that is the single highest-leverage thing in this whole series — because once you see it, a large family of “find the minimum X such that Y” problems stops being a family and becomes one template. This is the third of three posts on Joseph Choi’s binary search session deck. Part one covered the ten problems where a sorted array supplies the predicate; part two removed the sorting and replaced it with local comparisons and reference READ MORE
Binary Search Without a Sorted Array: Peaks and Rotations in C++
Every binary search in part one had a sorted array underneath it. Take that away and most people assume the technique goes with it. It does not — sortedness was never the requirement, only the most convenient way to meet it. This is the second of three posts on Joseph Choi’s binary search session deck. Seven problems here, in two families: three where the array rises and then falls, and four where a sorted array has been rotated. In both, something other than the sort order tells you which half to keep. As in part one, every listing was compiled READ MORE
Binary Search in C++: The Boundary Template and 10 Sorted-Array Problems
Binary search is the algorithm everyone knows and almost nobody writes correctly on the first try. The reason is not the idea, which is two lines. It is that every failure mode is silent: no crash, no timeout, just a wrong index. This is the first of three posts working through Joseph Choi’s binary search session deck in C++. Between them they cover twenty-two LeetCode problems, and they are split by the only question that matters — where does the monotonicity come from? This post takes the ten problems where it comes from the sort order, and sets up the READ MORE