1-1 pattern

Level: Intermediate

A side-by-side 1-1 along a wall pushes the mine outward.

This is a signature pattern that arises when two 1s sit side by side along an edge or the border of an open area. Even if the front 1 has two candidate mine cells, when the back 1 shares one of them, the position gets narrowed down.

As a result, the cell both 1s see together is confirmed safe, and the mine gets 'pushed' to the outer cell in the direction of travel. You can apply it repeatedly as you move along the wall.

You can process it quickly by eye without notes or flags, making it a very handy intermediate pattern for cleaning up edges.

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