Fillomino Solver, Step by Step
Type the given numbers and leave the other squares blank. Groups are outlined as they are filled in.
How to use the fillomino solver
Set the width and height, then type the numbers your puzzle gives and leave the rest blank. If the puzzle only uses small numbers, set the largest number allowed: the daily one never goes above 5. Press Explain the next step: the solver fills in what is certain, crosses out numbers that cannot fit, outlines each group as it forms, and says why. Show the answer fills the whole grid and checks the solution is the only one.
The rules of fillomino
Write a number in every square so that the grid splits into groups, each group of joined squares with the same number having exactly that many squares: a 3 sits in a group of three 3s. Two groups of the same size may not touch along a side, because they would then be a single group too big for its number. Numbers already given can be part of the same group or different ones.
How to solve fillomino, step by step
Close finished groups. When a group has its full size, no square beside it can carry the same number. Grow groups with one way out. A group still short of its size that has only one square it can grow into takes it. Look for cramped spaces. A number cannot go where there is not room for a group that big, so a pocket of three squares holds no 4. Watch for merges. A number that would join two groups of the same number into one too big cannot go between them. When those run out, the solver tries a number and keeps it only if it does not lead to a dead end.
How it was checked
The solver was run on all 150 puzzles of the daily fillomino. It found each stored answer and found it to be the only one when numbers go up to 5, as the daily puzzle allows, and every step it explained was checked against those answers: it never placed or crossed out a number wrongly. With no limit on the numbers, one of the 150 has a second answer that uses a group of six. It was also run on larger grids with groups up to seven.
More logic puzzles
There is a new daily fillomino every day. The suguru solver and the shikaku solver divide grids into regions the same way. For a puzzle you hold in your hands, see our brain teasers. There are more solvers on the puzzle tools page.
Puzzles you can hold
Packing puzzles from the shop: every piece has to fit.
Frequently Asked Questions
How do you solve fillomino?
Close off finished groups, since no square beside a complete group can have its number, and grow any group that has only one square it can grow into. A number also cannot go where there is no room for a group that big, or where it would join two groups of its number into one too large.
What are the rules of fillomino?
Write a number in every square so that each group of joined squares with the same number has exactly that many squares. Groups of the same size may not touch along a side.
Can two fillomino groups with the same number touch?
Only at a corner. Along a side they would join into one group, too big for its number.
Does every fillomino have one solution?
A well-made one does, often only once you know the largest number allowed. The solver checks, and says if the numbers you entered allow more than one.