Expert Train Tracks #4

12×12 · Milo · puzzle 4 of 20

Solving notes

This expert grid starts with 14 pieces in place (including A and B), and its route covers 86 of the 144 squares.

Where to start

No row or column here is 0, 1 or completely full, so begin at A and B and count the lines they sit in.
Counting and the two-connections rule alone fix 38 of the 86 track squares and rule out 11 squares.

Rows are numbered from the top, columns from the left.

What it takes

This one goes beyond a single “what if”: expect a longer chain of reasoning in the middle of the grid. The techniques are explained on the strategy page.

Show what counting alone proves (spoiler)

Orange lines are forced connections, dots are squares that must hold track, Xs are squares proven empty.

Stuck? Check shows mistakes for a few seconds, Hint fixes the next square along the route from A, and Solution shows the whole answer.