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"0" means grass everywhere

A row or column numbered 0 is finished the moment you see it.

The rule of thumb: A row or column with a 0 holds no tents — grass every clearing on sight and move on.

A "0" on the edge means that line holds no tents, so every clearing in it is grass — no counting, no judgement call. Mark the whole line the moment you spot it and move on; it’s the only move in the game that asks nothing of you.

The grass earns its keep twice over. It shrinks every line that crosses it, and a tree standing in a zero line can only take its tent from the other direction. These practice boards are picked so the zeroes matter: skip them and the rest of the reasoning stalls before the win.

Where to look: The zeroes, first thing, on every board — then the trees standing in those lines, whose tents have one direction fewer.

Worked example

A real position from a board that needs "0" means grass everywhere. Purple: what the reasoning rests on. Dashed: the cells in question. Green: what it proves.

Row 2 (its count is purple) needs no tents at all. The dashed cells are the clearings in it that are still open.

Row 2 needs no tents at all — every clearing in it is grass.

Practice it ↓