RecursionWordSplit.py

# Work split
# Author: Pradeep K. Pant, ppant@cpan.org

# Create a function called word_split() which takes in a string phrase 
# and a set list_of_words. The function will then determine if it is 
# possible to split the string in a way in which words can be made from the 
# list of words. You can assume the phrase will only contain words found in 
# the dictionary if it is completely splittable.

# Implement recusion word_split()
def word_split(phrase,list_of_words, output = None):
     # Checks to see if any output has been initiated.
    # If you default output=[], it would be overwritten for every recursion!
    if output is None:
        output = []
    
    # For every word in list
    for word in list_of_words:
        
        # If the current phrase begins with the word, we have a split point!
        if phrase.startswith(word):
            
            # Add the word to the output
            output.append(word)
            
            # Recursively call the split function on the remaining portion of the phrase--- phrase[len(word):]
            # Remember to pass along the output and list of words
            return word_split(phrase[len(word):],list_of_words,output)
    
    
    # Finally return output if no phrase.startswith(word) returns True
    return output        
# Test
    #out = word_split('themanran',['the','ran','man'])
    #print (out)
    print (word_split('themanran',['the','ran','man']))
    # ['the', 'man', 'ran']
    #print (word_split('ilovedogsJohn',['i','am','a','dogs','lover','love','John']))
    # ['i', 'love', 'dogs', 'John']
    #print (word_split('themanran',['clown','ran','man']))
    # []