WRITING
Notes on building and running systems
Engineering write-ups — architecture, security, and the occasional war story.
#hard · All writing
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01
Largest Rectangle in Histogram: the monotonic stack as a boundary oracle
Every bar in the histogram can be the height of a maximal rectangle — the question is how wide that rectangle can stretch. A monotonic stack answers that in O(n) by telling you exactly when each bar's reign as the minimum height is over. Here is how brute force makes the problem clear, and why the stack makes it fast.Jun 14, 2026 · 12 min read · #00060
02
N-Queens: placing conflict under constraint, then pruning the tree
N-Queens is backtracking stripped to its skeleton — place a queen row by row, check three independent conflict channels, undo on failure. This article works through all three approaches (brute force, row-by-row backtracking, and set-optimized backtracking), traces the n=4 decision tree by hand, and explains why the diagonal math falls out of one arithmetic insight.Jun 14, 2026 · 15 min read · #00087
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