Forcing Chain

Level: Advanced

Once one block's place is fixed, neighboring blocks are pushed one after another.

When a particular block's position in a line is pinned to a single spot, the possible ranges of the blocks before and after it shrink as well. Following this chain lets you confirm several cells at once.

By accounting for the minimum gaps required between blocks, fixing one block determines the earliest position where the next block can start. Pushing this lower bound all the way to the end of the line aligns the middle blocks.

This advanced technique applies edge forcing and overlap in a chain, and it is especially powerful on lines with densely packed clues.

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