# Sudoku at Between Waters

Sudoku (or su doku) puzzles are a test of logical thinking. Each puzzle
consists of a 9x9 grid of cells arranged in nine row, nine columns, and
nine 3x3 blocks. Some cells have values filled in. You must fill in the rest
of the cells so that each row, each column, and each block contains the digits
1 through 9 once each. Depending on the initial values, puzzles range from
easy to very difficult.

Between Waters provides daily sudoku puzzles as well as an interactive
solver for puzzles you find elsewhere.

## Daily Puzzles

Between Waters provides a daily sudoku puzzle in two formats:
The interactive puzzles have the following features:

**Reset** clears any values you have entered.
**Check** finds any incorrect values you have entered.
**Hint** solves for one cell.
**Solution** displays the solution to the puzzle.

The Hint function uses human-like logic to solve for one of the
next easiest cells. You can use this to help you learn how to solve
sudoku puzzles. When you get stuck, click the Hint button and then
try to figure out how you could have solved for that cell.

## Puzzle Solver

The interactive solver lets you get hints and
solutions for sudoku puzzles you find in newspapers, books, etc. It has
the same buttons as the daily interactive puzzle plus two others:

**Lock**. Click this button after you have entered the values
from the original puzzle. It locks those values in place so they
cannot be changed (even when you press the Reset button).
**Erase**. Click this button to erase the values in all the
cells including the locked values.

After you invoke the solver, enter the printed values from the
original puzzle. Make sure you have entered the values correctly and
then click the Lock button. At this point, the solver checks whether
it can solve the puzzle. You can then enter your own values and get
hints or the solution.

The solver is not perfect. You might find some particularly nasty
puzzles that it cannot solve. It is a work in progress.

## Troubleshooting

Although the sudoku applications do not use popups, they might
confuse some security software. If you don't see the puzzles,
you might need to temporarily disable your popup blocker.

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