Hard Train Tracks #4

10×10 · Devious · puzzle 4 of 40

Solving notes

This hard grid starts with 4 pieces in place (including A and B), and its route covers 55 of the 100 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 11 of the 55 track squares, though they rule out no squares yet.

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

What it takes

Our logic engine solves this puzzle with counting, the no-loop and no-early-finish rules and a one-step “what if” test. 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.