I just implemented a code in Scala to solve such puzzles. I am just using recursion to solve the problem. In short, for each word, I find all possible slots, and pick a slot and fill it with the word, and try to solve the partial puzzle with recursion. If the puzzle cannot be filled with the rest of words, it tries another slot, etc. if not, the puzzle is solved.
Here is the link to my code:
https://github.com/mysilver/AMP/blob/master/Crossword.scala
