Large print Masyu

How to solve a masyu

Draw one closed loop through the centres of cells so it runs straight through every white circle and turns on every black one. Cells with no circle are free, and the loop need not visit them.

The method

1. 1Start with the circles on the edge. A white circle in the top or bottom row has no vertical option, so the loop must run across it; one in the left or right column must run down it. A black circle near an edge can only send that leg inward, and it has to reach two cells, which fixes a surprising amount for free.
2. 2Extend every black circle two cells. The loop turns on a black and then runs straight for a full cell on both sides, so each black gives you three segments at once as soon as you know which way it turns. Two blacks a single cell apart can never both point at each other.
3. 3Look for whites in a row. A run of white circles in a line all go straight, so the loop crosses the whole run. The turn each one needs has to happen at one end or the other, which often decides the end of the run.
4. 4Remember a white's turn is close. A white is not just a straight. It also promises a corner within one cell on at least one side, so a white in the middle of a long straight run is impossible. That rules out more lines than it looks like.
5. 5Refuse the early loop. If closing a line would make a small ring while any circle is still off it, that closure is wrong. There is only one loop in the finished puzzle, and every circle is on it.

The one rule

One closed loop through cell centres, no branches and no crossings, straight through every white circle and turning on every black one.

What the answer page shows

The finished loop is printed at the back.

How the grades differ

Harder grades are bigger boards with fewer circles, so longer stretches of the loop come from the degree rule rather than from a circle.

Good for

Solvers who like a puzzle with two rules and a lot of consequence.