In this video, I'm just going to go through some of the basic terminology and
rules of Sudoku. So this is really kind of like a domain
analysis for the problem we're about to solve.
So first, Sudoku is played on a nine by nine board.
because it's nine by nine, the board has 81 of what we're going to call squares.
In addition to the 81 squares, we say that the board has 9 rows, because it's a
nine by nine board, nine columns. Cause it's a nine by nine board, and it
also has nine boxes, where the boxes are little three by three blocks of the whole
board. And so there's three boxes at the top,
three boxes kind of in the middle and three boxes at the bottom.
So, the rows, the columns and the boxes together, comprised what are called
units. There's 27 total units, because there's
nine rows, nine columns, and nine boxes. And adding nine, nine and nine gets 27.
So there's 27 total units and now we have enough terminology to concisely say the
goal of the game. The goal of the game is to fill every
square with a natural number from one to nine, but making sure there's not a
duplicate number in any unit. So there can't be a single row that has a
duplicate number in it. There can't be a single column that has a
duplicate number in it. And there can't be a single box that has
a duplicate number in it. Because we have the term unit we can say
that more concisely as there can't be a single unit that has a duplicate number
in it. So just to be clear, this is an illegal
move. You can't put a six in that third box in
the first row, because there's already a six in that row.
So that's an illegal move. Here's another illegal move, you can't
put a one there because there's already a one in that column.
So that's an illegal move. And here's another illegal move.
You can't put a three there, you can't put the red three in because there's
already a three in that box. That's an illegal move.
Again, the goal of the game is to fill in every square.
Was a natural from one to nine inclusive, but making sure that there's not a
duplicate number in any unit. So that's the quick terminology of Sudoku
and a quick summary of the rules. Again, if you've never seen Sudoku before
and you'd like a bit more detailed introduction to the rules of the game.
Just do a web search and find one of the many Sudoku sites, and you can play one
or two quick games before picking up the next video.