Futoshiki puzzles are built on square grids of typically 5x5 cells (although puzzles having sizes in the range 4x4 up to 8x8 can also
be made). To solve them you must place numbers into the puzzle cells in such a way that each row and column contains each of the digits less than
the size of the puzzle. In this respect they are similar to Sudoku puzzles. To give the solver a start, there will normally be several numbers
already in the puzzle.
In addition, a few pairs of adjacent cells will have
< and
> symbols inserted between them to indicate the
relative sizes of the numbers within those cells.
Any character which is typed at the keyboard will be placed into the focus cell (outlined in red), provided that it is not greater
than the dimension of the puzzle.
The location of the focus cell may be shifted by means of the cursor control keys or by pointing and clicking with the mouse.
Under default conditions, the program displays in each unsolved cell, the set of candidate symbols which might legally be placed
into that cell. Whenever a solution symbol is placed into one of the cells, the list of candidate symbols in other cells is automatically updated.
By the application of some logical reasoning, you will see that certain of the listed candidate symbols cannot possibly be a solution
for the cell in which they are shown. Such candidates may be removed by pointing and clicking with the mouse. When the last candidate symbol is
removed from a cell, it becomes the solution symbol for that cell.