Solution: The Fifteen Cent Flip

The challenge in the puzzle was to switch the position of a nickel and a dime in a rectangular array using the fewest number of moves possible. It was stated that the minimum number of moves needed to switch the coins is fewer than 20, but more than 12. The puzzle can actually be solved in 17 moves by following the sequence given below. In each step the direction the coin moves is indicated. Due to the arrangement of the array, there is only one coin that can move in the direction indicated for a given step, so which coin is moving has not been specified.

  1. Left
  2. Down
  3. Right
  4. Right
  5. Up
  6. Left
  7. Down
  8. Left
  9. Up
  10. Right
  11. Right
  12. Down
  13. Left
  14. Up
  15. Left
  16. Down
  17. Right

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