1. Scan for the most constrained lines
Begin with clues that occupy most of their line. Add the clue numbers and the minimum one-cell gaps between groups. The closer that total is to the line length, the fewer arrangements are possible.
For a 10-cell line with clues 4 3 1, the groups need 8 filled cells plus 2 mandatory gaps. The fit is exact, so the entire line can be placed immediately.
2. Use overlap on large clues
Place the same group mentally as far left and as far right as possible. Any cells shared by both placements must be filled. For a line of length L and one clue C, the guaranteed overlap is 2C − L cells whenever C is greater than half of L.
3. Push groups from confirmed edges
If a filled cell touches the edge and belongs to a clue of 4, the next three cells inward are also filled. The same principle works after an X: once a group is forced into the remaining segment, treat that segment like a smaller line.
4. Close groups as soon as they are complete
A run that already matches its clue cannot grow. Mark X immediately before and after it. These Xs often split a difficult line into two simpler independent sections.
5. Match groups to available spaces
After X marks divide a line, compare each open segment with the remaining clue sizes. A clue of 5 cannot fit inside a four-cell segment, so it belongs elsewhere. Sometimes only one clue can occupy a particular segment.
6. Cross-check after every useful move
Do not finish one row in isolation. Every filled or crossed cell changes one row and one column. Alternating between them prevents missed deductions and is much faster on 15×15 or larger grids.
What to do when you are stuck
- Rescan lines with the highest filled-plus-gap total.
- Check completed groups for missing X marks.
- Look for a clue that fits only one remaining segment.
- Inspect edges and cells adjacent to confirmed runs.
- Use one hint to learn the deduction, then explain why it is forced before moving on.
If a puzzle still appears inconsistent, copy its clues into the Picross solver to check whether a valid solution exists.
Large-grid comfort tips
Turn on guide lines every five cells and row/column focus. On mobile, the board scrolls while keeping a minimum cell size, so 20×20 and 25×25 grids remain readable instead of shrinking into tiny tap targets.
Practice on today's puzzle