X-Wing Sudoku Technique — Classic Fish Pattern Guide

An X-Wing can be found when two match up perfectly in parallel . We can then safely remove candidates in the opposite lines.

How it works

Find the first Row or Column

This Row has a . Digit 1 appears in exactly two cells.

Find the matching Row

This Row also has 1 in exactly two cells and in the same Columns.

Only 1s in each Row

These are the only four Cells that can be 1 in both Rows.

Notice the relationship

If this Cell is 1, then the opposite Cell must be 1.

And vice versa

If this Cell is 1, then the opposite Cell must be 1.

There's only two outcomes

In each Row, one of these Cells is 1. The opposite Cell will be 1 too. With this relationship, no other Cell in either Column can possiblly be 1.

Eliminate other cells

We can safely remove 1 from any other Cell in those two Columns.

1
3
7
4
1
3
6
7
9
3
6
5
6
7
8
2
2
3
5
7
8
2
3
5
6
8
9
4
2
3
6
2
3
8
5
6
7
3
5
7
1
2
3
5
8
2
3
5
6
8
2
3
6
8
7
1
2
3
8
4
3
5
9
3
9
1
2
7
8
1
2
6
8
1
2
6
7
8
3
2
7
9
1
7
8
4
5
4
1
2
3
5
6
8
2
7
1
7
9
1
3
7
9
3
7
9
9
3
8
3
7
8
5
4
1
2
6
3
7
8
6
2
3
5
8
9
2
3
4
8
1
3
5
7
9
3
7
5
7
8
9
5
7
9
4
7
8
9
1
5
7
1
4
8
5
9
6
3
2
4
9
1
3
5
8
1
3
5
8
9
1
3
8
2
3
5
7
9
4
1
5
7
8
9
1
5
7
9
6
Find the first Row or Column
This Row has a . Digit 1 appears in exactly two cells.
1
3
7
4
1
3
6
7
9
3
6
5
6
7
8
2
2
3
5
7
8
2
3
5
6
8
9
4
2
3
6
2
3
8
5
6
7
3
5
7
1
2
3
5
8
2
3
5
6
8
2
3
6
8
7
1
2
3
8
4
3
5
9
3
9
1
2
7
8
1
2
6
8
1
2
6
7
8
3
2
7
9
1
7
8
4
5
4
1
2
3
5
6
8
2
7
1
7
9
1
3
7
9
3
7
9
9
3
8
3
7
8
5
4
1
2
6
3
7
8
6
2
3
5
8
9
2
3
4
8
1
3
5
7
9
3
7
5
7
8
9
5
7
9
4
7
8
9
1
5
7
1
4
8
5
9
6
3
2
4
9
1
3
5
8
1
3
5
8
9
1
3
8
2
3
5
7
9
4
1
5
7
8
9
1
5
7
9
6
Find the matching Row
This Row also has 1 in exactly two cells and in the same Columns.
1
3
7
4
1
3
6
7
9
3
6
5
6
7
8
2
2
3
5
7
8
2
3
5
6
8
9
4
2
3
6
2
3
8
5
6
7
3
5
7
1
2
3
5
8
2
3
5
6
8
2
3
6
8
7
1
2
3
8
4
3
5
9
3
9
1
2
7
8
1
2
6
8
1
2
6
7
8
3
2
7
9
1
7
8
4
5
4
1
2
3
5
6
8
2
7
1
7
9
1
3
7
9
3
7
9
9
3
8
3
7
8
5
4
1
2
6
3
7
8
6
2
3
5
8
9
2
3
4
8
1
3
5
7
9
3
7
5
7
8
9
5
7
9
4
7
8
9
1
5
7
1
4
8
5
9
6
3
2
4
9
1
3
5
8
1
3
5
8
9
1
3
8
2
3
5
7
9
4
1
5
7
8
9
1
5
7
9
6
Only 1s in each Row
These are the only four Cells that can be 1 in both Rows.
1
3
7
4
1
3
6
7
9
3
6
5
6
7
8
2
2
3
5
7
8
2
3
5
6
8
9
4
2
3
6
2
3
8
5
6
7
3
5
7
1
2
3
5
8
2
3
5
6
8
2
3
6
8
7
1
2
3
8
4
3
5
9
3
9
1
2
7
8
1
2
6
8
1
2
6
7
8
3
2
7
9
1
7
8
4
5
4
1
2
3
5
6
8
2
7
1
7
9
1
3
7
9
3
7
9
9
3
8
3
7
8
5
4
1
2
6
3
7
8
6
2
3
5
8
9
2
3
4
8
1
3
5
7
9
3
7
5
7
8
9
5
7
9
4
7
8
9
1
5
7
1
4
8
5
9
6
3
2
4
9
1
3
5
8
1
3
5
8
9
1
3
8
2
3
5
7
9
4
1
5
7
8
9
1
5
7
9
6
Notice the relationship
If this Cell is 1, then the opposite Cell must be 1.
1
3
7
4
1
3
6
7
9
3
6
5
6
7
8
2
2
3
5
7
8
2
3
5
6
8
9
4
2
3
6
2
3
8
5
6
7
3
5
7
1
2
3
5
8
2
3
5
6
8
2
3
6
8
7
1
2
3
8
4
3
5
9
3
9
1
2
7
8
1
2
6
8
1
2
6
7
8
3
2
7
9
1
7
8
4
5
4
1
2
3
5
6
8
2
7
1
7
9
1
3
7
9
3
7
9
9
3
8
3
7
8
5
4
1
2
6
3
7
8
6
2
3
5
8
9
2
3
4
8
1
3
5
7
9
3
7
5
7
8
9
5
7
9
4
7
8
9
1
5
7
1
4
8
5
9
6
3
2
4
9
1
3
5
8
1
3
5
8
9
1
3
8
2
3
5
7
9
4
1
5
7
8
9
1
5
7
9
6
And vice versa
If this Cell is 1, then the opposite Cell must be 1.
1
3
7
4
1
3
6
7
9
3
6
5
6
7
8
2
2
3
5
7
8
2
3
5
6
8
9
4
2
3
6
2
3
8
5
6
7
3
5
7
1
2
3
5
8
2
3
5
6
8
2
3
6
8
7
1
2
3
8
4
3
5
9
3
9
1
2
7
8
1
2
6
8
1
2
6
7
8
3
2
7
9
1
7
8
4
5
4
1
2
3
5
6
8
2
7
1
7
9
1
3
7
9
3
7
9
9
3
8
3
7
8
5
4
1
2
6
3
7
8
6
2
3
5
8
9
2
3
4
8
1
3
5
7
9
3
7
5
7
8
9
5
7
9
4
7
8
9
1
5
7
1
4
8
5
9
6
3
2
4
9
1
3
5
8
1
3
5
8
9
1
3
8
2
3
5
7
9
4
1
5
7
8
9
1
5
7
9
6
There's only two outcomes
In each Row, one of these Cells is 1. The opposite Cell will be 1 too. With this relationship, no other Cell in either Column can possiblly be 1.
1
3
7
4
1
3
6
7
9
3
6
5
6
7
8
2
2
3
5
7
8
2
3
5
6
8
9
4
2
3
6
2
3
8
5
6
7
3
5
7
1
2
3
5
8
2
3
5
6
8
2
3
6
8
7
1
2
3
8
4
3
5
9
3
9
1
2
7
8
1
2
6
8
1
2
6
7
8
3
2
7
9
1
7
8
4
5
4
1
2
3
5
6
8
2
7
1
7
9
1
3
7
9
3
7
9
9
3
8
3
7
8
5
4
1
2
6
3
7
8
6
2
3
5
8
9
2
3
4
8
1
3
5
7
9
3
7
5
7
8
9
5
7
9
4
7
8
9
1
5
7
1
4
8
5
9
6
3
2
4
9
1
3
5
8
1
3
5
8
9
1
3
8
2
3
5
7
9
4
1
5
7
8
9
1
5
7
9
6
Eliminate other cells
We can safely remove 1 from any other Cell in those two Columns.

All Hints

Unlock hints to find
the X Wing on your board.

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