Slitherlink Solver

To find a single continuous path (in black) round the area, where the number of lines around any square equals the number in the square.

You can select one of various puzzles. Restart reloads the selected puzzle. You can also save the puzzle, perhaps prior to a guess, and later restore it.

Each line can be undefined (by default), black (ie set) or white (not set).

You can solve it interactively. If you click near a line in a square it will change that line to its next state.

A series of rules have been programmed to help in the solution - though more are needed. You can try each in turn (often many times) or press All which applies each once.

These rules include special cases like corners, if the cell has 0, 3 or 2 walls, rules for working if a line must be set or not, and one which checks if a line encloses a path too small.

The program determines if all squares are correct and there is one continuous path.

Backtracking can be used, though this generally only works if the board is nearly right, otherwise the search is aborted after 1000000 moves. Backtrack Next Free uses the next undecided line. Backtrack Next Fewer, chooses a cell with the fewest number of undecided lines.

You are told if it is solved and how many moves were taken. If you press NextMove it will step through these, whereas ShowMoves will automate this: you can slow or speed this.