Hashiwokakero (Bridges) Solver

Fri, 10 Jul 2026 08:09:53 +1000

hashiwokakero (“build bridges”, nikoli) hands you a grid of numbered islands and asks you to join them with bridges until every number is spent. it is the friendliest possible introduction to constraint satisfaction: the constraints are few and visual, propagation alone solves most human-published puzzles, and when it doesn’t, you get to write a backtracking search. this page documents my solver at code/private/hashi/ — a go rewrite of a uni assignment originally in c — including the debugging session that writing this page forced on it. 𐃏

Constraint-Propagation on Aayush Bajaj's Augmenting Infrastructure

Hashiwokakero (Bridges) Solver