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SEN LLC

I build small, focused tools and ship them open-source. Based in Japan 🇯🇵 with SEN LLC, working through a 100+ portfolio at sen.ltd/portfolio. Posts about TypeScript, AWS, and bugs that taught me so

Location Tokyo, Japan Joined Joined on  Personal website https://sen.ltd

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Engineer at SEN LLC

Statue Park: the no-touching rule isn't a rule, and the circle that names nothing costs 60% more
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Statue Park: the no-touching rule isn't a rule, and the circle that names nothing costs 60% more

#typescript #algorithms #gamedev #puzzle
1
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8 min read

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Country Road: contract the countries and it is a Hamiltonian cycle — and that is the easy half
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Country Road: contract the countries and it is a Hamiltonian cycle — and that is the easy half

#typescript #algorithms #gamedev #puzzle
1
Comments
7 min read
Creek: a puzzle with a closed form, and why the numbers on the edge of the paper are the ones to erase
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Creek: a puzzle with a closed form, and why the numbers on the edge of the paper are the ones to erase

#typescript #algorithms #gamedev #puzzle
1
Comments
8 min read
Numbrix: one number colours the whole board, and the ruler rung that provably pays nothing
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Numbrix: one number colours the whole board, and the ruler rung that provably pays nothing

#typescript #algorithms #gamedev #puzzle
1
Comments
9 min read
Kojun: the clue you draw before you write a digit, and two walls where boards stop existing
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Kojun: the clue you draw before you write a digit, and two walls where boards stop existing

#typescript #algorithms #gamedev #puzzle
1
Comments
6 min read
Magnets: a clue that can't see half the board, and a generator that cannot dead-end
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Magnets: a clue that can't see half the board, and a generator that cannot dead-end

#typescript #algorithms #gamedev #puzzle
1
Comments
6 min read
Doppelblock: a clue that doesn't say which cells it's about, and four rules that never change the answer
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Doppelblock: a clue that doesn't say which cells it's about, and four rules that never change the answer

#typescript #algorithms #gamedev #puzzle
1
Comments
9 min read
Nanro: the digit you never choose, and a clue that is two facts - each worthless without the other
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Nanro: the digit you never choose, and a clue that is two facts - each worthless without the other

#typescript #algorithms #gamedev #puzzle
1
Comments
7 min read
Kropki: every constraint lives inside a line - an exact per-line solver, and the silence between the dots carries the game
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Kropki: every constraint lives inside a line - an exact per-line solver, and the silence between the dots carries the game

#typescript #algorithms #gamedev #puzzle
Comments
5 min read
Tilepaint: a nonogram whose lines share variables - one subset-sum law at three strengths, and ambiguity a probe can't see
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Tilepaint: a nonogram whose lines share variables - one subset-sum law at three strengths, and ambiguity a probe can't see

#typescript #algorithms #gamedev #puzzle
Comments
5 min read
Chocona: every clump is a rectangle - a global law, its local 2x2 double, and engines that machine-check the equivalence
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Chocona: every clump is a rectangle - a global law, its local 2x2 double, and engines that machine-check the equivalence

#typescript #algorithms #gamedev #puzzle
Comments
7 min read
Aqre: the clue budget is the partition — and the solver ladder is hollow in the middle
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Aqre: the clue budget is the partition — and the solver ladder is hollow in the middle

#typescript #algorithms #gamedev #puzzle
Comments
7 min read
Nurimisaki: clue positions the setter never chooses — and half the information lives in the blank cells
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Nurimisaki: clue positions the setter never chooses — and half the information lives in the blank cells

#typescript #algorithms #gamedev #puzzle
Comments
6 min read
Kurotto: the puzzle with no global rule — and the first crack in the probe-equals-uniqueness law
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Kurotto: the puzzle with no global rule — and the first crack in the probe-equals-uniqueness law

#typescript #algorithms #gamedev #puzzle
Comments
6 min read
Cave: every answer is a hole-free polyomino — counted as lattice cycles, generated with a 3 3 stamp
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Cave: every answer is a hole-free polyomino — counted as lattice cycles, generated with a 3 3 stamp

#typescript #algorithms #gamedev #puzzle
Comments
6 min read
Yin-Yang: two global rules force one unbroken curve — every solved board is literally a yin-yang symbol
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Yin-Yang: two global rules force one unbroken curve — every solved board is literally a yin-yang symbol

#typescript #algorithms #gamedev #puzzle
Comments
6 min read
Gokigen Naname (Slant): the no-loop rule is a counting theorem — every board is a forest with exactly 2n+1 trees
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Gokigen Naname (Slant): the no-loop rule is a counting theorem — every board is a forest with exactly 2n+1 trees

#typescript #algorithms #gamedev #puzzle
Comments
5 min read
Tentai Show: one mirror map is the whole puzzle, and every deduction happens twice or not at all
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Tentai Show: one mirror map is the whole puzzle, and every deduction happens twice or not at all

#typescript #algorithms #gamedev #puzzle
Comments
6 min read
Shakashaka: the rule is about whole regions, and it is exactly a rule about one lattice point
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Shakashaka: the rule is about whole regions, and it is exactly a rule about one lattice point

#typescript #algorithms #gamedev #puzzle
Comments
11 min read
Tatamibari: three of the four rules are an exact-cover matrix, and the fourth is the one that matters
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Tatamibari: three of the four rules are an exact-cover matrix, and the fourth is the one that matters

#typescript #algorithms #gamedev #puzzle
Comments
10 min read
Ripple Effect: the rule that matters most never shows up in the difficulty rating
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Ripple Effect: the rule that matters most never shows up in the difficulty rating

#typescript #algorithms #gamedev #puzzle
Comments
9 min read
Solving Kurodoko: whether a rule looks useless depends on where you measure it
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Solving Kurodoko: whether a rule looks useless depends on where you measure it

#typescript #algorithms #gamedev #puzzle
Comments
6 min read
Solving Yajilin: clues can pin the shading, but they can never steer the loop
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Solving Yajilin: clues can pin the shading, but they can never steer the loop

#typescript #algorithms #gamedev #puzzle
Comments
8 min read
Solving Fillomino: the third rule isn't a rule — it's why the puzzle can be printed with no borders
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Solving Fillomino: the third rule isn't a rule — it's why the puzzle can be printed with no borders

#typescript #algorithms #gamedev #puzzle
Comments
7 min read
Solving LITS: the puzzle whose name is a theorem, and uniqueness means killing tetromino slides
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Solving LITS: the puzzle whose name is a theorem, and uniqueness means killing tetromino slides

#typescript #algorithms #gamedev #puzzle
Comments
7 min read
Solving Norinori: the puzzle with nothing written on it
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Solving Norinori: the puzzle with nothing written on it

#typescript #algorithms #gamedev #puzzle
Comments
7 min read
Solving Heyawake: compiling the one rule that crosses rooms into clauses
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Solving Heyawake: compiling the one rule that crosses rooms into clauses

#typescript #algorithms #gamedev #puzzle
Comments
7 min read
Solving Tapa: when the clue is a pattern, not a number, enumeration stops collapsing
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Solving Tapa: when the clue is a pattern, not a number, enumeration stops collapsing

#typescript #algorithms #gamedev #puzzle
Comments
6 min read
Solving Thermometers: the enumeration rule that won Kakurasu provably collapses into interval arithmetic
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Solving Thermometers: the enumeration rule that won Kakurasu provably collapses into interval arithmetic

#typescript #algorithms #gamedev #puzzle
Comments
4 min read
Solving Suguru: Sudoku with no rows, where a block's witnesses fire outward
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Solving Suguru: Sudoku with no rows, where a block's witnesses fire outward

#typescript #algorithms #gamedev #puzzle
Comments
6 min read
Solving Kakurasu: every line is a subset sum, and the size dial is the difficulty dial
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Solving Kakurasu: every line is a subset sum, and the size dial is the difficulty dial

#typescript #algorithms #gamedev #puzzle
Comments
6 min read
Solving Dominosa: the puzzle where nothing is hidden, and the rule I measured into irrelevance
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Solving Dominosa: the puzzle where nothing is hidden, and the rule I measured into irrelevance

#typescript #algorithms #gamedev #puzzle
Comments
8 min read
Solving Binairo with a line dictionary: every human trick is one projection
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Solving Binairo with a line dictionary: every human trick is one projection

#typescript #algorithms #gamedev #puzzle
Comments
3 min read
Solving Aquarium with subset-sum DP: gravity turns every tank into a chain
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Solving Aquarium with subset-sum DP: gravity turns every tank into a chain

#typescript #algorithms #gamedev #puzzle
Comments
5 min read
Solving Tents and Trees with bipartite matching: Hall's theorem as a puzzle move
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Solving Tents and Trees with bipartite matching: Hall's theorem as a puzzle move

#typescript #algorithms #gamedev #puzzle
Comments
4 min read
Solving Skyscrapers by projecting permutations: a line has n! futures, not n^n
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Solving Skyscrapers by projecting permutations: a line has n! futures, not n^n

#typescript #algorithms #gamedev #puzzle
Comments
4 min read
Solving Futoshiki with bounds propagation: one-edge rules, chain-length conclusions
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Solving Futoshiki with bounds propagation: one-edge rules, chain-length conclusions

#typescript #algorithms #gamedev #puzzle
Comments
4 min read
Solving Hitori with constraint propagation: the puzzle where propagation can't even start
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Solving Hitori with constraint propagation: the puzzle where propagation can't even start

#typescript #algorithms #gamedev #puzzle
Comments
5 min read
Solving Shikaku with constraint propagation: when the unknown is a rectangle, not a cell
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Solving Shikaku with constraint propagation: when the unknown is a rectangle, not a cell

#typescript #algorithms #gamedev #puzzle
Comments
5 min read
Solving Nurikabe with constraint propagation: three-valued cells, a reachability flood, and a uniqueness proof
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Solving Nurikabe with constraint propagation: three-valued cells, a reachability flood, and a uniqueness proof

#typescript #algorithms #gamedev #puzzle
1
Comments
4 min read
Solving Masyu with constraint propagation: an edge model, local patterns, a closure guard, and a uniqueness proof
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Solving Masyu with constraint propagation: an edge model, local patterns, a closure guard, and a uniqueness proof

#typescript #algorithms #gamedev #puzzle
Comments
4 min read
Solving Star Battle with Constraint Propagation and a Uniqueness Proof
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Solving Star Battle with Constraint Propagation and a Uniqueness Proof

#typescript #algorithms #constraintsolving #gamedev
Comments
5 min read
Solving Hashiwokakero (Bridges) with Constraint Propagation and a Connectivity Check
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Solving Hashiwokakero (Bridges) with Constraint Propagation and a Connectivity Check

#typescript #algorithms #constraintsolving #gamedev
Comments
6 min read
Solving Kakuro (Cross Sums) with Constraint Propagation — Sum-Combination Domains, Fewest-Candidate Search, and Puzzles Proven Unique
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Solving Kakuro (Cross Sums) with Constraint Propagation — Sum-Combination Domains, Fewest-Candidate Search, and Puzzles Proven Unique

#typescript #algorithms #constraintsolving #gamedev
Comments
3 min read
Solving Akari (Light Up) with Constraint Propagation — Fixpoint Wall/Sight/Illumination Rules, Darkest-Cell Search, and Puzzles Proven Unique
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Solving Akari (Light Up) with Constraint Propagation — Fixpoint Wall/Sight/Illumination Rules, Darkest-Cell Search, and Puzzles Proven Unique

#typescript #algorithms #constraintsolving #gamedev
Comments
3 min read
Solving Slitherlink with Constraint Propagation — Fixpoint Clue/Vertex Rules, Closed-Loop Pruning, and Puzzles Proven Unique
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Solving Slitherlink with Constraint Propagation — Fixpoint Clue/Vertex Rules, Closed-Loop Pruning, and Puzzles Proven Unique

#typescript #algorithms #constraintsolving #gamedev
Comments
3 min read
Solving Nonograms with Constraint Propagation — Memoized Placement Intersection, Fixpoint Sweeps, and No-Guessing Puzzles by Construction
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Solving Nonograms with Constraint Propagation — Memoized Placement Intersection, Fixpoint Sweeps, and No-Guessing Puzzles by Construction

#typescript #algorithms #constraintsolving #gamedev
Comments
2 min read
Solving Sokoban Backward — Provable Dead Squares via Pull-BFS, and a Push-Optimal BFS Solver
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Solving Sokoban Backward — Provable Dead Squares via Pull-BFS, and a Push-Optimal BFS Solver

#typescript #algorithms #search #gamedev
Comments
3 min read
Solving the 15-Puzzle with Permutation Parity and IDA* — Proving Sam Loyd's 14-15 Swap Impossible Without Search
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Solving the 15-Puzzle with Permutation Parity and IDA* — Proving Sam Loyd's 14-15 Swap Impossible Without Search

#typescript #algorithms #search #gamedev
Comments
3 min read
Solving Lights Out with GF(2) Linear Algebra — the Whole Puzzle Is One Matrix Equation, plus the 5 5 Quiet Patterns and the Solvability Rate
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Solving Lights Out with GF(2) Linear Algebra — the Whole Puzzle Is One Matrix Equation, plus the 5 5 Quiet Patterns and the Solvability Rate

#typescript #algorithms #math #gamedev
Comments
3 min read
Building a Boids Flocking Simulation in TypeScript — a Murmuration from Three Local Rules, with a Pure, Testable Engine
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Building a Boids Flocking Simulation in TypeScript — a Murmuration from Three Local Rules, with a Pure, Testable Engine

#typescript #canvas #simulation #algorithms
Comments
3 min read
Building an Infinite-Sequence CLI in Haskell — Laziness and Lists That Refer to Themselves, plus a Prime Sieve and Hamming Numbers
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Building an Infinite-Sequence CLI in Haskell — Laziness and Lists That Refer to Themselves, plus a Prime Sieve and Hamming Numbers

#haskell #functional #algorithms #cli
Comments
3 min read
Building a Leftist Heap CLI in OCaml — It's All merge, a Persistent (Immutable) Priority Queue, and an O(log n) Right Spine
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Building a Leftist Heap CLI in OCaml — It's All merge, a Persistent (Immutable) Priority Queue, and an O(log n) Right Spine

#ocaml #functional #algorithms #datastructures
Comments
3 min read
Building a Fenwick Tree (BIT) CLI in Zig — It All Hangs on i & -i: O(log n) Prefix Sums, Point Updates, and Binary-Lifted Select
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Building a Fenwick Tree (BIT) CLI in Zig — It All Hangs on i & -i: O(log n) Prefix Sums, Point Updates, and Binary-Lifted Select

#zig #algorithms #datastructures #cli
Comments
3 min read
Building an Aho–Corasick CLI in Go — Match a Whole Dictionary in One Pass, Failure Links as Generalized KMP, and Every Overlapping Match
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Building an Aho–Corasick CLI in Go — Match a Whole Dictionary in One Pass, Failure Links as Generalized KMP, and Every Overlapping Match

#go #algorithms #strings #cli
Comments
3 min read
Building a Cuckoo Filter CLI in Rust — the Deletion a Bloom Filter Can't Do, Partial-Key Cuckoo Hashing, and a High Load Factor via Relocation
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Building a Cuckoo Filter CLI in Rust — the Deletion a Bloom Filter Can't Do, Partial-Key Cuckoo Hashing, and a High Load Factor via Relocation

#rust #algorithms #datastructures #cli
Comments
3 min read
Building a t-digest CLI in Go — Stream p50/p99/p99.9 in a Few KB, a Scale Function That Keeps Tails Sharp, Exact min/max, and Mergeable Digests
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Building a t-digest CLI in Go — Stream p50/p99/p99.9 in a Few KB, a Scale Function That Keeps Tails Sharp, Exact min/max, and Mergeable Digests

#go #algorithms #datastructures #cli
Comments
3 min read
Building a Count-Min Sketch CLI in Rust — Sizing from a Target Error, d Counters from Two Hashes, No Underestimates, and Mergeable Sketches
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Building a Count-Min Sketch CLI in Rust — Sizing from a Target Error, d Counters from Two Hashes, No Underestimates, and Mergeable Sketches

#rust #algorithms #datastructures #cli
Comments
4 min read
Building a HyperLogLog CLI in Go — One Billion Distinct in 16 KB, a Harmonic Mean, a Hash Finalizer, and Mergeable Sketches
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Building a HyperLogLog CLI in Go — One Billion Distinct in 16 KB, a Harmonic Mean, a Hash Finalizer, and Mergeable Sketches

#go #algorithms #datastructures #cli
Comments
4 min read
Building a Bloom Filter CLI in Rust — Sizing from a Target FP Rate, k Hashes from Two, and Guaranteed No False Negatives
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Building a Bloom Filter CLI in Rust — Sizing from a Target FP Rate, k Hashes from Two, and Guaranteed No False Negatives

#rust #algorithms #datastructures #cli
Comments
4 min read
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