The Sudoku generator that ships in my puzzle game is a plain randomised-backtracking solver. It works, but "it works" is a vibe, not a number. So I pointed three different solving strategies at the exact same engine and counted how hard each one actually has to search.
The engine and the benchmark are open source. Every node count below is deterministic — clone it, run node benchmark.js, and you get the same figures I did.
The setup
A grid is a flat array of 81 cells (0 = empty). The corpus is 40 puzzles — 10 each of Easy, Medium, Hard and Expert — generated by the shipped generator with fixed seeds, so the exact same 40 puzzles rebuild every run.
The metric I care about is search nodes: how many cells the solver has to guess at and recurse on. Wall-clock time depends on your laptop; node counts don't. (Times below are from my machine, rounded, for flavour only.)
