Nonogram
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8×8 Nonogram Solver — Step-by-Step Solutions for Every Configuration

The 8×8 Nonogram Solver processes any valid 8×8 Japanese crossword, Griddler, or Picross clue configuration and returns the complete solution — or, for puzzles requiring hypothesis testing, the step-by-step logical path through which the solution is reached. The solver applies the same constraint-propagation and hypothesis-selection algorithms used by advanced human solvers, making it a precise and transparent tool for both unblocking specific puzzles and understanding the logical structure of 8x8 configurations.

How to Use the Solver

Step 1 — Enter your clues: Input the clue sequences for all 16 lines of your 8×8 puzzle — the row clues in order from top to bottom, and the column clues from left to right. Each clue is entered as a space-separated sequence of numbers (e.g., "3 2 4" for a three-block clue). The solver validates each entry against the line length to catch input errors before processing begins.

Step 2 — Run the solver: Click Solve. The solver processes your 64-cell configuration through its constraint-propagation and hypothesis-selection algorithm and returns the complete solution grid, with each cell clearly marked as filled or empty.

Step 3 — Review the solution path: The solver displays not just the final solution but the step-by-step logical path used to reach it — which lines were resolved in which order, which constraints forced each cell confirmation, and (for Expert through Evil configurations) which hypothesis cells were selected and what cascade they produced. This step-by-step output is the primary learning tool the solver provides.

Step 4 — Return to playing: Use the solution path to identify where your own solving approach diverged from the optimal path, then return to the puzzle and continue from your current position — or start a fresh puzzle with improved technique. The solver is designed to accelerate your development as a 8x8 solver, not to replace the solving experience.

How the 8×8 Solver Algorithm Works

Initialisation phase: For an 8×8 grid, the solver initialises 16 line constraint sets across 64 cells. Eight-cell lines can carry up to four blocks with meaningful combined slack, producing arrangement sets of up to twelve valid configurations per line. The solver enumerates all arrangements using a recursive placement algorithm that processes blocks left-to-right and backtracks when minimum-gap constraints are violated.

Constraint propagation phase: Propagation operates across the 16-line network using an arc-consistency algorithm: for each confirmed cell, the solver immediately reduces arrangement sets in all intersecting lines and requeues those lines for further confirmation extraction. This arc-consistency approach ensures that every inference available from a confirmed cell is extracted before the solver advances to the next propagation step.

Hypothesis resolution phase: For 8×8 configurations requiring hypothesis testing, the solver implements a look-ahead mechanism: before committing to a hypothesis, the solver performs a two-step propagation from each candidate cell under both assumptions and selects the candidate whose more constrained assumption produces the highest immediate confirmation count. This look-ahead significantly reduces the depth of hypothesis chains required at Expert through Evil difficulty.

Accuracy and Reliability

The 8×8 solver is guaranteed to find the unique solution to any well-formed 8×8 nonogram — a puzzle constructed so that exactly one cell configuration satisfies all clue constraints simultaneously. For puzzles with ambiguous clue sets (where multiple valid solutions exist), the solver identifies the ambiguity and reports which cells have multiple valid states rather than selecting arbitrarily among valid solutions.

All solutions returned by the solver are verified against the complete clue set before display — ensuring that the solution reported is always valid, never partial, and never the result of an incorrect hypothesis branch that was not properly resolved.

When to Use the Solver

The solver is most valuable in four specific situations:

Blocked at a specific point: You've applied every technique you know to every 8x8 line and cannot identify the next confirmed cell. The solver identifies the exact next deduction — whether a standard elimination or a hypothesis step — and explains why it follows from the current constraint state.

Learning hypothesis technique: You're developing hypothesis-and-verify skills and want to compare your hypothesis selection to the solver's. The solver's hypothesis target, assumption direction, and cascade sequence provide a concrete benchmark for evaluating your own selection strategy.

Verifying a partial solve: You want to confirm that your current grid state — with some cells already confirmed — is consistent with the unique solution before investing further time in the puzzle.

Post-solve analysis: You've completed the puzzle independently and want to understand whether the path you took was optimal — or whether there was a shorter sequence of deductions that would have reached the same solution in fewer steps.

Play 8×8 Nonograms

Ready to put the solver's insights into practice? The 8×8 puzzles are available across all six difficulty levels:

→ 8×8 Easy → 8×8 Medium → 8×8 Hard

→ 8×8 Expert → 8×8 Extreme → 8×8 Evil

FAQ

Yes — the solver processes any valid 8×8 clue set where the sum of each row's clue values (plus minimum gaps) does not exceed 8 cells, and similarly for columns. Clue sets that violate these constraints are flagged as invalid before processing begins.

No — the solver operates independently of your puzzle session. Entering your clues into the solver and reviewing the solution does not modify your in-progress puzzle. You can return to your puzzle at any stage and continue from exactly where you left off.

Yes — the solver handles all difficulty tiers including Evil, which requires nested hypothesis trees. The solver's hypothesis-selection and cascade-propagation algorithms are designed specifically to handle the deep conditional reasoning that Evil 8x8 configurations require, and the 8×8 solver resolves hard configurations in under three seconds and expert configurations in under eight seconds. evil configurations — requiring nested hypothesis trees — complete within fifteen to twenty seconds.

If the clue configuration you enter has no valid solution — either because of an input error or a genuinely infeasible clue set — the solver reports this explicitly rather than returning an incorrect partial result. Check your clue entries against the original puzzle to identify any transcription errors.