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  • Lesson 4 of 7
  • Patterns
  • 3 min

The 1-1 Pattern in Minesweeper

Some cells can't be solved by looking at one number, only by looking at two together. The simplest of these patterns is the 1-1. It turns up wherever two 1s sit side by side against a wall.

Step 1 of 4

  1. Two 1s against a wall

    The 1 in row 4, column 1 sits against the left edge of the board. It touches just two hidden cells: the one above it and the one above it on the right. One of those two is its mine. The 1 beside it, in row 4, column 2, touches those same two cells and one more, the starred cell. It has only one mine too, and that mine is in the two cells it shares, so the third cell is safe. This is the 1-1 pattern.

  2. Open the third cell

    Which of the two shared cells is the mine? The 1s can't say. But they don't need to: the cell only the second 1 touches is safe either way.

    Your move

    Open the cell the two 1s prove safe.

  3. A flag can make a 1

    Patterns hide inside bigger numbers. The 1 in row 5, column 3 touched one hidden cell, so that cell, in row 4, column 4, is flagged now. The 2 in row 5, column 4 touches that flag, so it needs just one more mine: read it as a 1. Under it, the 1 in row 6, column 4 sits on the bottom edge and touches two hidden cells, and the 2 touches both of them. A 1 and a "1" against a wall: it's a 1-1, standing on its end.

    Your move

    Find the cell this 1-1 proves safe, and open it.

  4. No wall, no pattern

    Two 1s side by side again, in row 4, columns 3 and 4. Is the starred cell, above the second 1 on its right, safe?

    Question

What you learned

  • Two 1s side by side against a wall: the cell only the second 1 touches is safe.
  • More generally: if every hidden cell of one number also touches a second number, and they need the same number of mines, the second number's other cells are safe.
  • A wall is anything that leaves the first 1 no hidden cell of its own: the board's edge or an opened cell.
  • Take the flags off a number before you read a pattern: a 2 beside a flag is a 1.
  • Without a wall the first 1 has a cell of its own, and the pattern proves nothing.

In this course

Unit 1The rules

  1. Minesweeper Rules: Reveal, Numbers and Flags
  2. Chording in Minesweeper: Open Cells With a Double-Click

Unit 2Patterns

  1. Minesweeper Strategy: Two Rules for Mines and Safe Cells
  2. The 1-1 Pattern in Minesweeper
  3. The 1-2 Pattern in Minesweeper
  4. The 1-2-1 Pattern in Minesweeper
  5. The 1-2-2-1 Pattern in Minesweeper

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