safe puzzle

[alison6399]

In the above table, each of the buttons must be pressed once only in the corrcet order to open the safe at X. 3D is 3 down 1l is 1 left, etc. Which button is the 1st u must press - Pse show workings. Thanx


3D 1R 1D 3L 2DD
4R 2R 1L 1U 1U
2D 2R 1D 2D 4L
2U 1U 1R 2L X
4R 4U 2U 2L 1U

[grasscarp]

2u (in bottom row) 1d 1r 2l 1u 2r 2d sl 4u 1r 1d 1l 2r 1u 3l 3d 2u 4r 1u 2d 4l 2d 4r 1u x

[crofter]

alison You should start at the X and work through the sequence BACKWARDS!

From X the last move must be 1U, preceded by 4R, then 2D, then 4L, 2D, 1U, 4R, 2U, 3D, 3L, 1U, 2R, 1L, 1D, 1R, 4U, 2L, 2D, 2R,1U, 2L, 3L,1U, 2R (25th button)

So START with 2R (2nd Row, 2nd Column) and trace back through the above sequence must lead to X (unless I've made a slip somewhere)!

[crofter]

I DID make a slip in the last three steps which should read
.... 2L, 1R, 1D, 2U!

This new sequence reverses to give grasscarp's solution.

At least you now know how to obtain the solution!

[crofter]

Since all the moves are "forced", you can start with ANY button and follow through the steps to arrive at X (but you won't necessarily have 25 steps).

SInce 2U (on the bottom row) cannot be reached from any other button on the bottom row or any other button in the middle column, it follows that this is where to start the sequence and get all 25 steps before arriving at X.