Question

I’m working on a game and I’m struggling to get some generic functionality. Suppose we have a phrase like "puzzle game using group of words" so I generate possible subsets from this:

"puzzle", "game", "using", "group", "of", "words" and to add more fun I also add group of two consecutive words (for now groups of > 2 words are not allowed): "puzzle game", "game using", "using group", "group of", "of words"

So now the main idea would be forming ALL possible combinations from these subsets that form the original sentence. Please note that in this case the subsets should be a partition.

Example:

"puzzle game", "using", "group", "of words"
"puzzle", "game", "using group", "of", "words"

…

Not allowed:

"puzzle game", "game using", .. (it's not a partition as "game" is repeated)

Is there any known algorithm that generates all possible combinations? I presume this can get very time consuming for longer phrases so are there alternatives that try to find possible best options based on some weight for example?

I don’t pretend to get code (though that would be awesome) but at least any tip or ideas of where to look at would be really appreciated!

Answer 1

first parse your string into words, let the list of words be S. create an empty result list (let it be L) of possible return values.

use a recursive solution: set a current solution (initialized to empty), and at each step – add the possible next word/double to it. when you used up your words, the ‘current’ will be a partition, and add it to the list.

pseudocode:

partitions(S,L) = partitions(S,L,{})

partitions(S,L,current):
   if S is empty: 
        L.add current
   else:
        first <- S.first
        second <- S.second
        partitions(S-{first}-{second},L,current+{first second})
        partitions(s-{first},L,current+{first})

EDIT: note: this solution assumes only 1 or 2 words are legal per partition. if it is not the case, instead of the hard-coded recursive call which decreases S by 1/2 words, you will have to iterate over the 1,…,S.size() first words.

None recursive solution (using Stack and List ADTs):

partitions(S):
   L <- empty_result_list()
   stack <- empty_stack()
   stack.push(pair(S,{}))
   while (stack is not empty):
      current <- stack.pop()
      S <- current.first
      soFar <- current.second
      if S is empty:
          L.add(soFar)
      else:
          stack.push(pair(S-{S.first}-{S.second},soFar+{S.first S.second})
          stack.push(pair(S-{S.first},soFar+{S.first})
   return L