generatedAt string | engine string | rows list | summary dict |
|---|---|---|---|
2026-09-13T14:18:39.372Z | full-tree minimax (perfect play, no pruning) | [
{
"firstMove": "corner",
"cellExample": 0,
"nodesEvaluated": 59705,
"replyBestScore": 0,
"xOutcomeIfPlayedHere": "draw"
},
{
"firstMove": "edge",
"cellExample": 1,
"nodesEvaluated": 63905,
"replyBestScore": 0,
"xOutcomeIfPlayedHere": "draw"
},
{
"firstMove": "cent... | {
"emptyBoard": {
"toMove": "X",
"nodesEvaluated": 549946,
"bestScore": 0,
"outcome": "draw"
},
"everyFirstMoveDrawsOrWinsForX": true
} |
Tic-Tac-Toe Solver Benchmark — Minimax Game-Tree Size
How many positions the LK Forge Tic-Tac-Toe Solver evaluates to play perfectly. The shipped engine is a full-tree minimax (no alpha-beta pruning) with a depth-preferring score, so it enumerates the entire game tree.
- How the solver works: https://lkforge.com/tools/puzzles/tic-tac-toe-solver/how-the-tic-tac-toe-solver-works.html
- Try it: https://lkforge.com/tools/puzzles/tic-tac-toe-solver/
- Producer: LK Forge — client-side AI games, solvers, and tools.
Headline numbers
- From the empty board, X to move, the solver evaluates 549,946 positions — exactly the size of the full tic-tac-toe game tree. The result: a draw with perfect play.
- Every legal first move draws or wins for X — X can never lose from any opening if it plays perfectly.
- Nodes to evaluate a single first move (opponent to reply): corner 59,705 · edge 63,905 · center 55,505. The centre opening is the cheapest to search because it constrains the reply tree most.
Files
data/tic-tac-toe-benchmark.json— empty-board node count & outcome, per-opening node counts, and the perfect-play summary.
Method
- Engine: the scoring functions copied verbatim from the shipped
tic-tac-toe-solver.js(DOM stripped) with a node counter added — the numbers describe the exact shipped search. - Node = one call to the recursive
score()evaluator.
Reproduce
node scripts/benchmark-tic-tac-toe.mjs
Citation
LK Forge (2026). Tic-Tac-Toe Solver Benchmark — Minimax Game-Tree Size. https://lkforge.com/tools/puzzles/tic-tac-toe-solver/
Everything runs client-side, no login, no tracking.
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