Split string into words

Question

I am looking for the most efficient algorithm to form all possible combinations of words from a string. For example:

Input String: forevercarrot

Output:

foreve         


        

Answer 1

A psuedocode implementation, exploiting the fact that every part of the string needs to be a word, we can't skip anything. We work forward from the start of the string until the first bit is a word, and then generate all possible combinations of the rest of the string. Once we've done that, we keep going along until we find any other possibilities for the first word, and so on.

allPossibleWords(string s, int startPosition) {
    list ret
    for i in startPosition..s'length
        if isWord(s[startPosition, i])
            ret += s[startPostion, i] * allPossibleWords(s, i)
    return ret    
}

The bugbear in this code is that you'll end up repeating calculations - in your example, you'll end up having to calculate allPossibleWords("carrot") twice - once in ["forever", allPossibleWords["carrot"]] and once in ["for", "ever", allPossibleWords["carrot"]]. So memoizing this is something to consider.