how to play
Shape Up might look intimidating at first but it's really not, sure the puzzle is complicated but think about it like this:
Shape Up is a mathematical puzzle where we have three rods (A, B, and C) and N disks. Initially, all the disks are stacked in decreasing value of diameter i.e., the smallest disk is placed on the top and they are on rod A. The objective of the puzzle is to move the entire stack to another rod (here considered C), obeying the following simple rules:
- Only one disk can be moved at a time.
- Each move consists of taking the upper disk from one of the stacks and placing it on top of another stack i.e. a disk can only be moved if it is the uppermost disk on a stack.
- No disk may be placed on top of a smaller disk.
Take an example with 2 disks: Disk 1 on top of Disk 2 at peg A. The target is to move both these disks to peg B.
Looks simple, Right!
Move Disk 1 from peg A to peg C. Then move disk 2 from peg A to peg B and, finally, move disk 1 from peg C to peg B.
This solution takes 3 steps.
You can easily move this stack from peg B to any other peg using these 3 steps.
Move Disk 1 from peg A to peg C. Then move disk 2 from peg A to peg B and, finally, move disk 1 from peg C to peg B.
This solution takes 3 steps.
You can easily move this stack from peg B to any other peg using these 3 steps.
But what if we have 3 disks – 1,2, and 3 stacked in peg A.
To move the stack to peg B you would have to expose disk 3 and to do that disk 1 and 2 have to be moved to peg C.
So by ensuring that you do not break the rules, using the above subsets of 3 steps in the previous case, you would move disk 1 and 2 to peg C, leaving disk 3 exposed with no disk above it.
To move the stack to peg B you would have to expose disk 3 and to do that disk 1 and 2 have to be moved to peg C.
So by ensuring that you do not break the rules, using the above subsets of 3 steps in the previous case, you would move disk 1 and 2 to peg C, leaving disk 3 exposed with no disk above it.
Now to solve the problem, recursively move disk 3 from peg A to peg B.
Then disk 1 from peg C to peg A. After which disk 2 can be moved above disk 3 at peg B.
The puzzle is finally completed by moving disk 1 from peg A over disk 2 and 3 at peg B.
Then disk 1 from peg C to peg A. After which disk 2 can be moved above disk 3 at peg B.
The puzzle is finally completed by moving disk 1 from peg A over disk 2 and 3 at peg B.