You challenge is to find a route across a crocodile infested swamp using an inadequate selection of rather short planks. Thankfully the planks are light enough to move around and the swamp is full of old tree-stumps which will support the planks to form temporary bridges. So with careful planning and judicious re-use of planks you might just find a route. Needless to say you can only move planks you can physically reach so try not to leave a plank behind unless there is good reason to do so.
The best way to visualise the problem is to imagine yourself stuck in a real swamp, with tree-stumps too far apart to jump-between and planks too heavy to move more than one at a time. The remaining rules get a bit fiddley but here they all are. I recommend you try the warm-up puzzles below to explore the rules properly.
- You can pick up and carry a plank provided you have access to one end.
- You can only pick-up and carry one plank at a time.
- Planks must be supported both ends, and must be an exact fit.
- You cannot jump between stumps or planks.
- You cannot move a plank if you are already carrying one.
- Planks cannot be used diagonally, only north-south or east-west.
- Planks cannot support other planks, and cannot be stacked.
- Planks cannot bridge intermediate stumps or planks.
Cross the swamp from left to right.
Click on Restart to restart.
Click on Undo/Redo to replay previous moves.
Click on Replay to restart (with redo active).
Click on the play area to pick up or put down a plank. Accessible stumps will be automatically highlighted for you.
Two of five
Here are two of the original five puzzles which existed when the plank puzzles first went on-line in July 2000.
Deep-end (as in in-at-the...) was the first published puzzle for the 5x5 grid and for a long time the only one because I deemed the grid rather too small to be worthy of much attention.
Ironically, over the subsequent 10 years, I ended up hand-crafting hundreds more 5x5 puzzles to cater for three editions of the River Crossing puzzle sets. I could not have been more wrong about its potential!
Route-66 was one of the early large-grid plank-puzzles, designed by hand, long before there was any automated tools to check for short-cuts and verify shortest path. Manual checks seemed to indicate it took at least 66 moves (plank relocations) to solve which at the time seemed astounding and likely to be proven wrong (it was ultimately proven correct).
For an interesting view of Route-66 see its span diagram.
More to explore...
concept & maze designs - © Andrea Gilbert 2000-2001
planks applet - © Graham Rogers 2000-2001
applet hosted with permission from Graham Rogers
applet JS conversion - cheerpj transpiler from Leaning Technologies - 2020