Alien Dictionary

alien-dictionary.js

var words = [
  "wrt",
  "wrf",
  "er",
  "ett",
  "rftt"
]

var alphabet = []
var hash = {};

function insert(value) {
  if (alphabet.indexOf(value) == -1) {
    alphabet.splice(0, 0, value)
  }
}

function findKey(keys) {
  if (keys.length) {
    keys.map(function(key) {
      var values = hash[key]

      if (values && values.length) {
        values.map(function(value) {
          if (keys.indexOf(value) == -1) {
            insert(value)
            values.pop(value)
          }
        })

        delete hash[key]
        findKey(Object.keys(hash))        
      } else {
        insert(key)
      }
    })
  }
}

function decoder(words) {
  words.map(function(word, index, array) {
    var currentWord = word
    var nextWord = array[index + 1]
    
    if (!nextWord) { return }
 
    for (var i = 0; i < currentWord.length; i++) {
      var currentChar = currentWord.charAt(i)
      var comparisonChar = nextWord.charAt(i)

      if (currentChar !== comparisonChar) {
        if (hash[currentChar] && hash[currentChar].indexOf(comparisonChar) !== -1) {
          hash[currentChar].push(comparisonChar);
        } else {
          hash[currentChar] = [comparisonChar];          
        }
        return;
      }
    }
  })

  findKey(Object.keys(hash))
  console.log(alphabet)
}

decoder(words)