What is a Nonogram solver?
A Nonogram solver is a tool that takes the number clues from a picture logic puzzle and calculates which cells must be filled and which must stay empty. Nonograms are also widely known as Picross, Griddlers, Hanjie and Japanese crossword puzzles, so the same solver can help with all of those names.
The clues describe runs of filled cells. A row clue of 4 2 means there is a block of four filled cells, at least one empty cell, then a block of two filled cells. The solver compares every row clue with every column clue until the only matching picture grid remains.
- Enter row clues and column clues from a puzzle.
- Check whether the clues have a valid answer.
- Reveal the completed picture grid.
- Spot clue sets that are impossible or ambiguous.
How to use this Nonogram solver
Start by choosing the width and height of the puzzle. Width means the number of columns, and height means the number of rows. Then choose the group size, which controls how many clue number boxes appear for every row and column.
After you create the grid, type the column clues above the board and the row clues beside the board. Leave unused boxes blank. If a whole line has no filled cells, you can leave it blank or enter 0. Press Solve to calculate the answer.
- Choose Width, Height and Group size.
- Press Create grid.
- Enter the column clues from top to bottom.
- Enter the row clues from left to right.
- Press Solve to fill the answer grid.
How Nonogram clues work
Every clue number is a length of a filled block. Multiple numbers in one line always appear in the listed order, and separate blocks need at least one empty cell between them. The spaces before the first block and after the last block can be any length, including zero.
That simple rule is what makes Nonograms logical. If a run is long enough that all possible placements overlap, the overlapping cells must be filled. Once a run is fixed, the cells around it often become empty separators.
- A clue of 5 fills one group of five cells.
- A clue of 1 1 fills two single cells with at least one empty cell between them.
- A clue of 0 or a blank line means no cells are filled in that line.
- Rows and columns must agree on the same filled cells.
Why a puzzle can have no solution or many solutions
A valid Nonogram needs row clues and column clues that describe the same total number of filled cells. If the row clues add up to 32 filled cells but the column clues add up to 30, no solution can exist.
Some clue sets are balanced but still ambiguous. That means more than one picture grid satisfies every clue. A good published Nonogram usually has one unique solution, because uniqueness lets solvers progress by logic instead of guessing.
How this Nonogram solver works
The solver first generates all legal patterns for each row and column. It then removes patterns that contradict confirmed cells. Whenever all remaining patterns for a line agree on a cell, that cell is forced.
If forced logic does not finish the grid, the solver uses a controlled backtracking search. It chooses the row or column with the fewest remaining possibilities, tests one pattern, and keeps only branches that still satisfy every crossing clue.