- The New York Times introduced a new daily puzzle called Pips, where dominoes are placed on a grid with various constraints.
- The author used a constraint solver (MiniZinc) to solve Pips puzzles, finding it straightforward and taking under two hours from no prior knowledge.
- Constraint solvers allow expressing conditions directly, and the solver finds solutions automatically, often in milliseconds.
- Complications included unwanted multiple solutions from undefined empty cells, solver unpredictability, and debugging by removing constraints.
- Different solver backends (e.g., Gecode, Chuffed) had varying performance; Chuffed performed best for these puzzles.
- The solver works via backtracking search and constraint propagation, pruning the search tree efficiently.
- Using constraint solvers offers a higher-level programming paradigm, focusing on constraints rather than algorithms.