Use every clue, then close the line.
Sometimes a line has no spare space at all. Other times, the black groups are complete and only empty marks remain.
Count black cells and separators together. An exact fit gives the whole line; a completed line then helps its crossings.
Look for an exact fit
Add the clue numbers, then add one separator for each gap between consecutive groups. In a seven-cell line with clues 3 3, the black cells take six spaces and the required separator takes one. That uses all seven cells, so the answer is three black cells, one empty cell, then three black cells.
There is no optional space at either end in an exact fit. A single clue equal to the line length is the simplest case: a 5 in five cells fills the whole line. An empty line clue, shown as 0 here, means there are no black cells in that line.
Clues: 3 3
| Arrangement | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|
| Exact fit | black | black | black | empty | black | black | black |
Do not confuse spare room with a contradiction
Clues 2 2 in seven cells use at least five spaces. The two spare spaces may go at the start, at the end or between the groups. The clue alone does not tell you which arrangement is correct.
That line may become solvable after another row or column supplies information. Keep the candidates open rather than forcing a neat centered picture. The hidden image is the reward for the logic, not evidence you can rely on during the solve.
Close only a group that is certainly complete
Once a group has its full required length and you know which clue it belongs to, its adjacent cells must be empty unless the group touches an edge. These marks stop it from growing accidentally.
When every black group in a line is correctly placed, the remaining cells are empty. But an equal total of black cells is not enough on its own. Check group lengths and order too: one run of four does not satisfy clues 2 2.
Make a short row-and-column loop
After finishing a line, revisit the lines that cross the changed cells. This small loop is often more useful than repeatedly scanning the whole grid.
When the loop stops producing certain cells, try overlap or ask for a logical hint. A good hint explains a step that follows from the current board. If earlier marks make the puzzle impossible, correct that conflict first instead of building more deductions on top of it.
Try three small deductions
These are practice lines, not a saved game. Fill only what is certain; leave anything uncertain unknown.
Leave a separator
Two groups of 2 fill this line apart from their separator. Use Fill and Mark to finish it.
Clues: 2 2