Sudoku Luna
ExpertChains and uniqueness

Practise: Nice Loop

This puzzle is picked so that the easy moves run out and exactly the Nice Loop gets you going again. Solve as far as you can — when nothing obvious is left, the pattern is waiting for you.

Skip the obvious cells and start right where the technique is needed.

Practice
Mistakes0Score3,500Time0:00

How to spot it

Trace a sequence of candidates with alternating strong and weak links until it closes. Do not repeat a candidate before the loop closes. For a weak discontinuity, the start candidate is joined by weak links on both sides and can be crossed out. For a continuous loop, look outside the loop only at cells that see both ends of a weak same-digit link.

Put it to use

Where you will meet it

Expert grids are the only place this pattern regularly decides the solve. Bring your notes.

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Stuck on a grid of your own?

Type the position into the solver and it walks the whole solution, naming the technique behind every step — including this one.

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