WRITING
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#constraint-satisfaction · All writing
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01
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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