What is xy pattern in Sudoku?

An XY-Wing is a group of three cells, one sharing a unit with the other two, each having only 2 candidates. The two cells that share a unit with the first are called the Wings. Each of the wings must share one candidate with the first cell, (that's part of sharing a unit) but of different values.

How do you identify an XY chain in Sudoku?

The "X" and the "Y" in the name represent these two values in each chain link. If A7 is 5 then A3/C7/C9 cannot be. if A7 is NOT 5 then it's 9, so A5 must be 2, which forces A1 to be 6. If A1 is 6 then C2 is 5.

What is the easiest way to find xy chain in Sudoku?

To use XY-Chain, look for two bi-value cells (we'll call them "pincers") that can't see each other but that have at least one number in common (we'll call it the "shared number.") In the example below, our pincers are light green, and both of them have the same candidates.

What are the patterns in Sudoku?

Patterns are essentially a series of completed numbers (either givens or numbers that have been filled in) in a specific order in one of the boxes on the sudoku grid. Patterns help you organize the remaining numbers and eliminate possibilities in a box, and in related boxes, rows and columns.

What is the trick to solving Sudoku puzzles?

Sudoku Mastery: The Y Wing (or XY Wing)

How many patterns are possible in Sudoku?

There are exactly 6, 670, 903, 752, 021, 072, 936, 960 possible solutions to Sudoku (about 10^21) . That's far more than can be checked in a reasonable period of time.

What is the best order to solve Sudoku?

The easiest way starting a Sudoku puzzle is to scan rows and columns within each triple-box area, eliminating numbers or squares and finding situations where only a single number can fit into a single square. The scanning technique is fast and usually sufficient to solve easy puzzles all the way to the end.

What is the fastest algorithm for Sudoku?

Backtracking algorithm is the fastest algorithm to solve sudoku puzzles, It is by far the fastest compared to the other two methods. Also, let's note that each algorithm was faster with harder problems than with easier problems.

What is the best search algorithm for Sudoku?

Modelling Sudoku as an exact cover problem and using an algorithm such as Knuth's Algorithm X and his Dancing Links technique "is the method of choice for rapid finding [measured in microseconds] of all possible solutions to Sudoku puzzles." An alternative approach is the use of Gauss elimination in combination with ...

How can you tell a swordfish in Sudoku?

A Swordfish is a 3 by 3 nine-cell pattern where a candidate is found on three different rows (or three columns) and they line up in the opposite direction.

What is the unique rectangle rule in Sudoku?

A "Unique Rectangle" (UR) consists of four cells that occupy exactly two rows, two columns, and two boxes. All four cells have the same two candidates left (in real sudokus not all cells have to hold all of the UR candidates, see below).

What is the forcing chains strategy in Sudoku?

A simple forcing chain is when you have lots of cells with just 2 candidates - and whichever value you would choose for one cell forces another cell to be just one of its two values.

What is the XYZ rule in Sudoku?

More precisely an XYZ-Wing has three cells that contain only 3 different numbers between them, but which fall outside the confines of one row/column/box, with one of the cells (the 'apex' or 'hinge') being able to see the other two; those other two having only one number in common; and the apex having all three numbers ...

How do you find hidden pairs in Sudoku?

If you're looking for hidden pairs, you're looking for two numbers which only exist in two cells within that area – even though there will be other candidates in the same cell “hiding” them. For triples, you'll be looking for three cells, and so on.

What is the average time to solve a Sudoku?

It is believed that the average Sudoku player spends approximately 20 minutes solving a typical Sudoku puzzle. For very hard puzzles, that number can be much higher. While the game itself can be challenging and complex, several strategies can be used successfully to find the solution.

Is 6 minutes good for Sudoku?

5 minutes is more than enough time to jump start your brain, re-evaluate your Sudoku strategy, and develop a new perspective on how to view the Sudoku grid. So “take 5” and give yourself a new chance at solving Sudoku puzzles!

What is the 45 rule in Sudoku?

The 45 rule is a basic solving-technique in Killer Sudoku. Each house (row, column, nonet) must add to 45 (the sum of the digits 1 through 9).

Is Sudoku good for the brain?

Sudoku keeps your brain active and reduces the risk of Alzheimer's, a most common cause of dementia that affects a person's thinking and behavioural skills. Stimulates your mind: The game works on your logical thinking process as you are absorbed in solving a puzzle and eventually improve your number skills.

What is the rule of 3 Sudoku?

If three candidates can be found in only the same three Cells of a region (Row, Column or Square), then one of these candidates is the solution for the first of these Cells, a second one is the solution for the second Cell and the last candidate is the solution for the third Cell.

What is the one rule in Sudoku?

Sudoku Rule № 1: Use Numbers 1-9

Within the rows and columns are 9 “squares” (made up of 3 x 3 spaces). Each row, column and square (9 spaces each) needs to be filled out with the numbers 1-9, without repeating any numbers within the row, column or square.

Is it possible to do Sudoku without guessing?

Sudoku is a puzzle involving logic – no arithmetic or guessing is required! The basic idea of completing puzzles is to find cells (the small squares) where you are sure that only one value is a valid placement. If you've not played Sudoku before, take a look at our guide to how to start.

Can a Sudoku have 2 solutions?

A well-formed Sudoku puzzle is one that has a unique solution. A Sudoku puzzle can have more than one solution, but in this case the kind of logical reasoning we described while discussing solving strategies may fall short. There are examples of rank-3 Sudoku puzzles with 17 givens that are well-formed.