线索0是什么意思？

每个可能位于1和9之间的数字至少是2，所以即使是一个单个夹心单元格也会将和推到2或更多。和恰好为0的唯一方式是夹心为空——1和9必须占据连续单元格。注意顺序是自由的：1-然后-9和9-然后-1都满足线索，所以0线索告诉你它们接触，而不是哪个先出现。在九单元格行中，只有八个相邻单元格对，所以搜索空间立即坍缩。

Treat the 1 and 9 of a 0-clue line as a glued domino and test where the domino fits. Box constraints do most of the work: if box 1 already contains a 9, no domino cell inside box 1 may hold that line's 9. Crossing clues help too - If a column's clue forces its 1 far from a row's candidate domino positions, those positions die. Each elimination removes two cells at once, which is why 0 clues crack open faster than any other clue. The moment you place either the 1 or the 9 in that line, the partner digit is forced into an adjacent cell - Usually uniquely, once row and box exclusions are applied.

Puzzles often include 0 clues on intersecting lines. A row 0-clue and a column 0-clue that cross create a strong interaction: if the shared cell held the row's 1, the column would need its 9 directly above or below, and both placements can be tested against the boxes in seconds. Always resolve 0-clue lines first and revisit them after every few placements - They keep paying out as the grid fills in.