Hanjie Strategy Tips
Hanjie, or griddlers as some people refer to the puzzle, definitely take some getting used to.
They have less immediate appeal than perhaps the sudoku puzzle, but once you get into them they are just as addictive and fun to solve.
The main strategy with hanjie is to solve by looking at the rows or columns that have high numbers. If there is a number that is the width or height of the row, then you can immediately colour in that whole row.
Even if no row or column is wholly determined from the off, then you can often fill in at least part of a row. The rule to use is simple. If the number displayed is greater than half the length of the row/column, then you can fill in at least once cell in the centre of the puzzle.
That is because, whatever the exact position of the filled cells, all combinations will have certain cells at the centre in common. The simplest way to realise the truth of this is to look at a simple example. Here is a row from a puzzle of width five:
- - - - - 3
We can see that three cells are coloured in this row. Here are the combinations:
x x x - -
Now, we see that all three possible combinations have a square in common: the centre square. Thus we can mark this as filled without knowing the exact combination that is used in this particular hanjie puzzle.
Thus this is how you can determine at least one filled cell from seeing if the number at the end of a row/column is greater than half the length of the row/column.
Another important point to note is to place a '.' or mark of your choice in cells that you know CANNOT be filled in order to remind you of this fact and help you to solve the puzzles.
For instance, look at this line of a width-five puzzle which is already partially determined:
- x - - - 1, 1
Now, we know that there must be a gap of at least one cell between the two filled cells in this row, and therefore the cell to the right and left of the 'x' cannot be filled, thus we can mark them with a dot:
. x . - -
This is an essential solving aid and helps us remember that the other filled cell in that row can only be one of the final two cells of the row.
The other key strategy to bear in mind with solving hanjie is to apply your new knowledge to affected rows or columns. Whenever you have deduced something new about a cell - for instance that it is filled or perhaps cannot be filled, see what implication that has for the rest of that row and column.
By iterating through a puzzle in this manner you should be able to gradually work your way through. With harder puzzles, you may need to go through a puzzle several times, adding more filled cells gradually as you go through. Sometimes you can only move one step at a time; with simpler puzzles there may be several deducations you can make at any one time and more ways to proceed.
One thing is for sure - practice helps, and the more hanjie or griddler puzzles you do, the better and quicker at solving you will become. Good luck!