ROSECODE 130
Perfectly protected pillars
In the main hall of the King's palace there are pillars disposed in a rectangular grid N*M
The king wants to dispose 4 guards at the 4 directions of each pillar.
A guard at the east of a pillar is at the west of the next pillar, etc ...
Being mathematically inclined, the king wants that for each pillar, there are exactly 2 guards looking at it and 2 guards turning their back.
Here is an example with 2*3 pillars (and 17 guards):
How many possible configurations are there for 4*6 pillars?
You are given: 374 configurations for 2*3 pillars
[My timing: 25 sec]
The king wants to dispose 4 guards at the 4 directions of each pillar.
A guard at the east of a pillar is at the west of the next pillar, etc ...
Being mathematically inclined, the king wants that for each pillar, there are exactly 2 guards looking at it and 2 guards turning their back.
Here is an example with 2*3 pillars (and 17 guards):
| ↓ | ↑ | ↑ | |||||
| ← | O | → | O | → | O | ← | |
| ↑ | ↑ | ↓ | |||||
| → | O | → | O | → | O | → | |
| ↑ | ↑ | ↓ |
How many possible configurations are there for 4*6 pillars?
You are given: 374 configurations for 2*3 pillars
[My timing: 25 sec]