Slide Puzzle Solver

What people mean by a slide puzzle

In a one-blank grid, a slide puzzle and a sliding puzzle describe the same basic game. The pieces remain inside a rectangular frame, and a neighboring tile moves into the empty cell. Repeating those slides changes the arrangement until the numbered order or picture is restored. This page starts a 3x3 example in the sliding puzzle solver; you can switch to another supported square size in the tool.

The name alone can be misleading. A phone game might call a multi-cell block escape game a slide puzzle too. Some games let you slide an entire row around a loop, remove pieces, or pass through several empty cells. Those rules change which positions are reachable. This solver handles square 3x3 through 8x8 boards containing one-cell pieces and exactly one blank, so begin by checking that your game's moves match that model.

Identify the goal before the scramble

A numbered game often finishes in reading order with the blank at the bottom-right corner. A picture game finishes when each crop returns to its original place. Neither convention is guaranteed by the phrase slide puzzle. A game can put the blank in another corner or arrange numbers in a spiral. Look for its completed example before copying the starting position.

The default target is shown through the piece numbers. To change it, open More → Edit goal and arrange the target cells or type their sequence. Then return to Edit start and copy the scramble. The same set of labels must exist in both. A solver answer only makes sense relative to this pair of arrangements, not relative to the name printed on the game's menu.

Two input methods, one board model

If the pieces are numbered, open Type numbers in Edit mode. Read across the top row, continue on the next row, and include the blank as 0 or _. Spaces or commas separate the entries. A 3x3 board needs nine values, while a 5x5 board needs 25; in each case the labels start at one and finish just before the cell count. Validation catches duplicates and omissions.

For an image, use Photo to upload the completed picture, then match the scrambled pieces in Edit start. Their identities come from the goal image: piece one is the top-left crop, followed by the next crop to its right. Clicking two cells in the editor exchanges them so you can record any input arrangement. That editing action must not be confused with a legal slide during Play or playback.

Common patterns that look deceptively close

A nearly completed board can contain an awkward final pair. Both pieces may appear one cell from home, yet the blank is on the wrong side to place either without disturbing neighbors. A board with a complete top row may require preserving that row while cycling pieces underneath it. A photo with repeated texture can look complete even though two similar crops are exchanged.

These are reasons to enter the entire board, not just the pieces that look wrong. A route depends on where the blank and all neighboring tiles are. If the input fails the reachability check, inspect the goal and labels before assuming the puzzle itself is defective. The tool explains the parity mismatch and offers Fix it, which changes two numbered pieces. It does not create a legal route for an unchanged impossible position.

How to read an answer

Press Solve after the board matches your source. The answer names a tile and shows its sliding direction. If a tile above the blank moves downward, the tile arrow points down even though the blank ends up higher. This distinction matters when copying a move list into another game.

Replay can be paused, advanced one step at a time, or moved to a selected step. Keep your external board synchronized with the displayed replay; after an accidental move, return to a known step or enter the new arrangement. Move counts represent single-tile slides. A gesture that moves several aligned tiles corresponds to several moves even if the interface performs it with one click.

Why board size changes the search

For the 3x3 example, the solver builds a distance table from the chosen goal and follows decreasing distances. For 4x4, it can search with a heuristic and pattern databases while making a quick constructed route available. Larger boards use row-and-column placement, protect completed positions, and finish the remaining 3x3 region with a distance table. These are different ways of producing a replay under the same movement rules.

This naming page focuses on recognizing the game and recording it correctly. Choose a size page below when you need its particular parity rule or large-board placement advice. The picture and tile pages cover visual identification and alternative tile mechanics, respectively, so you can check that the solver represents your puzzle before following an answer.