Parity (Checkerboard) Search

Level: Basic

Fire on every other cell like a checkerboard to guarantee grazing the smallest ship.

If the shortest ship is two cells long, coloring the grid like a chessboard and firing only on cells of one color will still graze every ship at least once — because even a two-cell ship must occupy one cell of that color.

This cuts the number of cells you need to search in half, doubling your hunting efficiency. Checking just 50 of 100 cells is enough to pick up a lead on every ship.

Once the smallest remaining ship grows (for example, after all two-cell ships are sunk), you can widen the gap further — searching every third cell — to make the net even sparser.

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