GridWits
Hard tier Technique 22 of 31 Used by Smart Hint

Dead End

A line can never just stop — every dot touches zero or two line segments. Draw a candidate edge and follow where the line is forced to go: if it gets driven into a dot whose other edges are all crossed off, it dies in a dead end, so the candidate edge is ruled out.

How it works

  1. 1Could the highlighted edge be part of the loop? Suppose it is, and follow only the two rules every beginner already uses: a dot touches zero or two lines (never one, never three), and a clue with its count complete crosses off its remaining sides.
  2. 2Each step is forced — the line has exactly one way to continue, so it gets pushed along the highlighted path, one edge at a time.
  3. 3Four continuations in, the line is driven into a dot whose every other edge is already crossed off. It has nowhere to go — and a line can never just stop.
  4. 4A dead end means the supposition was wrong from the first stroke: cross off the highlighted edge. If you can spot the trapped pocket ahead of time, you don't even need to draw anything — the edge that leads into it can't be a line.
2 1 0 1 1 2 2 1 1 1 1 2
  • Edge on the loop
  • Edge ruled out
  • Cells that establish the pattern
Next in the ladder Shared-Dot Balance →

Several clues become linked because a dot fully enclosed by their cells must contain zero or two lines.