Train Tracks Solver

Train Tracks Solver — Step by Step

Type the counts along the top and right, click the left and bottom edges to move A and B, and add the given pieces. Then press Solve. Or play a generated puzzle and send it here with one click.

Train Tracks Solver: rules, how to use it, tips

Lay a single railway line from A to B through the squares, matching the row and column counts.

The rules

The track starts at A on the left edge and ends at B on the bottom edge.
It runs through the centres of squares, straight or turning a right-angle corner. It never branches, crosses itself or forms a loop.
The numbers say how many squares in each row and column contain track.
Some pieces are given and must be used as shown.

Using the solver

Choose the size, type the counts, set A and B, and add given pieces (or press Sample).
Press Solve and step through: empty lines, squares that need two joins, and joins that would close a loop.

Tips

Zeros and full lines. A 0 means the whole row or column is empty. A count equal to the line’s length means every square has track.
Extend the given pieces. A given piece points into its neighbours — those squares must continue the line.
Two joins. Every track square joins exactly two sides. A square that can only join one more way must use it.
No loops. Never join two ends of the same stretch of track — it would make a loop.

The full guide, with a worked example and common mistakes: How to play Train Tracks.

Questions

Can the track touch itself?

It can pass next to itself, but it never crosses, branches or joins into a loop.

Do the given pieces count?

Yes — a given piece is a track square and counts towards its row and column.

Is there always one answer?

Yes — every puzzle here is checked to have exactly one solution.

How do I solve one from a book?

Open the Train Tracks Solver, type the counts, set A and B, add the given pieces and press Solve.