Number of solutions

I've said before that there are quadrillions of solutions to Einstein's Sudoku.  This wasn't an exaggeration.  How do we find out how many solutions there are?  Well, first let's look at the 4x4 game.

In the first cell, in the upper left, there are four different different possibilities: the red, blue, orange, or green house.  Given after we choose one of these (let's say the orange house), then there are three possibilities for the next cell (the red, blue, or green house).  And after we choose one of those, there are two possibilities for the next house, and then only one choice left for the last house.

If you work out all the possible orders of the houses, there are 4 x 3 x 2 x 1 possibilities, which totals up to 24.  4 x 3 x 2 x 1 can also be written as "4 factorial," or "4!"

For each of the 24 ways there are to configure the houses, there are also 24 ways to arrange the people, 24 ways to arrange the fruit, and 24 ways to arrange the drinks.  The total amount of possible solutions on the 4x4 grid is 24 x 24 x 24 x 24.  Or 4! x 4! x 4! x 4!.  Or 4!⁴.

This totals up to 331,776 different possible solutions, just for the 4x4 grid.

For the 3x3 grid, there are 3! x 3! x 3!, or 3!³ solutions.  This totals up to 6³ or 216 solutions.

For the 5x5 grid, there are 5! x 5! x 5! x 5! x 5!, or 5!⁵ solutions.  That totals up to 24,883,200,000 (over 24 billion) possible solutions.

And lastly, for the 6x6 grid, there are 6!6 solutions, which is 139,314,069,504,000,000, over 100 quadrillion.

Difficulty modes

There are three different difficulty modes.  The tutorial mode is called 3x3:

It's called this, because there are three different categories of thing you need to figure out (people, house colors fruit, and drink), and each category contains three things.  This is a good starting point for any puzzler, but once you get used to it you can move up to 4x4 and the much more difficult 5x5 or 6x6 grids.  In these modes, there are more houses and each contains more things you need to place.  So in addition to which person, house color, fruit and drink, you will also need to figure out which pet goes where and which type of fish.

In all of the difficulty modes, however, it is completely possible to figure out the whole puzzle based on the clues you're given, so don't be afraid to try something more difficult!

How to play.

When you first open Einstein's Sudoku, you should see a screen like this:

This is the game screen.  At the top, you'll see a timer counting how long you've been playing and another one counting up your score.  Your score is the time it takes you to solve the puzzle, plus a penalty if you use any hints.  A lower score is better, and you can upload your score to the online leader-boards to see how well you do against your friends.  In between these two numbers is number of your randomly-generated puzzles.

Underneath that, we have the screen where you'll be doing most playing:

 Your job here is to figure out which person goes in which house, and which fruit they eat.   If you tap on any of the cells, it will bring it into focus:

If you know one of these houses definitely doesn't go in this spot, you can tap on it once to remove it.

Or, if you're sure that another color does go here, you can hold your finger on it to promote it, and remove all the other ones:

 When you do this, it automatically removes that color of house from all the other places.  You continue removing and promoting items until each space only has one person, one house, one fruit, and one drink in it.

But how do you know which items to remove and which to promote?  Well, that's where the clues come in.  Underneath the grid is a set of clues for each puzzle:

The clues on the left are very simple.  They tell you that the person in the orange house eats strawberries and also drinks coffee.  Clues here will always tell you that two things go together in the same house.  The clues on the right could tell you a couple things.  

If you see two items with an ellipses between them, like this: It means that the item on the left has to be left and the item on the right has to be on the right.  So in this picture, you would know that the man with the green background has to be to the right of the person who eats peppers.  It doesn't, however, mean that they are right next to eachother.

 If you see three items in a row, like this:it means that the item in the middle is between (and directly next to) the two items on the side.  So in this picture, we know that the  blue house is between the house where somebody drinks scotch and the house where somebody drinks coffee.  However, the person who drinks coffee could be on the left or the right.

If you see two items next to eachother, like this: it means that those two items will be next to eachother in the neighborhood, but either one could be on the left or the right.

Based on the information given in these clues, you have everything you need to know in order to gradually deduce who and what goes into each house in the grid above.  Sometimes, there will be more clues than fit on the screen, so if it seems like you don't know enough information, be sure to try scrolling in the clue windows!

Finally, at the bottom of the screen, you will see the options bar:

The  +  button on the left will refresh Einstein Sudoku and start a new puzzle for you.  The undo button will undo a step you've done in the game, and the redo button will undo an undo.

If you get stuck, you can press the "Clue" button.  This will either tell you what you can eliminate next.  Or, if you made a wrong move, it will tell you how many steps to go back.  Don't over-use it, though, because hints will add to your score.

If you forget how to play, the "?" button will give you a quick tutorial, and the last button on the right flips over to the options side of the screen:

From here, you can change the size of the game grid (which will change the difficulty), check your scores against your friends, and find out more about the app.

Happy puzzling!

What is Einstein's Sudoku?

Einstein's Sudoku is a fun, addictive puzzle game, being developed for the iTunes App store, to be played on any iOS device (iPhone, iPod touch, or iPad).

It has three difficulty levels, and is based on randomly-generated puzzle sets.  The basic format of the game is that players are given a set of clues, and from that must determine who lives in which house, and also different facts about those people.  It is based on a riddle, said to be invented by Albert Einstein, that goes like this:

1. There are five houses.
2. The Englishman lives in the red house.
3. The Spaniard owns the dog.
4. Coffee is drunk in the green house.
5. The Ukrainian drinks tea.
6. The green house is immediately to the right of the ivory house.
7. The Old Gold smoker owns snails.
8. Kools are smoked in the yellow house.
9. Milk is drunk in the middle house.
10. The Norwegian lives in the first house.
11. The man who smokes Chesterfields lives in the house next to the man with the fox.
12. Kools are smoked in a house next to the house where the horse is kept.
13. The Lucky Strike smoker drinks orange juice.
14. The Japanese smokes Parliaments.
15. The Norwegian lives next to the blue house.

Now, who drinks water? Who owns the zebra?

 Based on this information, puzzle solvers can piece together who lives in what house, what they own , and what they smoke, in order to find out the answers to the questions underneath.

Einsten's Sudoku works much like this puzzle, but with over a quadrillion possible solutions, it's a different game every time.

Introduction

Greetings, and welcome to the official blog for Einstein's Sudoku released by Helium Apps.

The purpose of this blog is to give general information about the app and also answer some questions that people may have.