ypapax / quiz

find the longest compound-word in the list - golang job interview task

quiz

Q: Given a list of words like https://github.com/NodePrime/quiz/blob/master/word.list find the longest compound-word in the list, which is also a concatenation of other sub-words that exist in the list. The program should allow the user to input different data. The finished solution shouldn't take more than one hour. Any programming language can be used, but Go is preferred.

Fork this repo, add your solution and documentation on how to compile and run your solution, and then issue a Pull Request.

Obviously, we are looking for a fresh solution, not based on others' code.

Go Solution

Build

go test && go build

Run

$ ./quiz /path/to/word.list
inputted words count 263534
The longest compound word is
antidisestablishmentarianisms
It has 29 characters
It consists of the following words:
[anti disestablishmentarian isms]

Algorithm

• Since we want the biggest compound word, sort all the words by length - biggest goes first
• For each word (compoundWordCandidate) starting from the first (biggest), find other words - its substrings and put them to subWords slice.

  for _, compoundWordCandidate := range sortedWords {
    var subWords []string
    for _, partWordCandidate := range sortedWords {
      if compoundWordCandidate == partWordCandidate {
        continue
      }
      if !strings.Contains(compoundWordCandidate, partWordCandidate) {
        continue
      }
      subWords = append(subWords, partWordCandidate)
      validParts := getCompoundParts(compoundWordCandidate, subWords)
      if len(validParts) == 0 {
        continue
      }
      compound = compoundWordCandidate
      parts = validParts
      return
    }
  }

• After every append to subWords, check if the slice has length more than 1 and try to build the current compoundWordCandidate from subWords using method getCompoundParts. If it returns positive length slice, that's it. Current compoundWordCandidate is the result of the program - the longest compound word. It consists of validParts.

• Function func getCompoundParts(wholeWord string, parts []string) (validParts []string) cuts off beginning and end of wholeWord reducing number of possible parts by 2 and calls itself with shorter wholeWord and lower length parts until has trivial cases when parts length is one or two.

Solution author

Maxim Yefremov upwork profile