Present and discover answers to the gopher problem.
You have five holes in your yard. You know that a gopher lives in one of them, and they are arranged in a line:
| Hole 1 | Hole 2 | Hole 3 | Hole 4 | Hole 5 |
|---|---|---|---|---|
| ? | ? | ? | ? | ? |
Every day at noon, you go out and you stab a single hole with a stake.
Every night the gopher must move holes, to either the right or left.
What is the fewest number of days you can guarantee the gopher is dead?
And what is the sequence of hole stabbings to provide that guarantee?
You do not know which hole the gopher occupies on Day 1.
If the gopher is on the end, he must move inwards; he cannot wrap around from Hole 1 to Hole 5 or vice versa.
Upon stabbing, you've either killed the gopher or you remove the stake and wait a day.
The gopher could choose to move in any sequence. For example, if you stab Hole 3 every day, the gopher could move from Hole 1 to 2 to 1, and back and forth forever, like so:
| - | Hole 1 | Hole 2 | Hole 3 | Hole 4 | Hole 5 |
|---|---|---|---|---|---|
| DAY 1 | G | O | X | O | O |
| DAY 2 | O | G | X | O | O |
| DAY 3 | G | O | X | O | O |
See READMEs of subfolders for solutions.