is_chain.py

valid_words = ['chair', 'racket', 'touch', 'height', 'tunic']


chain = []

def chain_words(available_words:[], current_word: str):
	chain.append(current_word)
	available_words.remove(current_word)

	for word in available_words:
		if word.startswith(current_word[-1]):
			chain_words(available_words, word) 

def is_chain(words: []) -> bool:
	chain_words(words, words[0])

	if len(chain) < len(words):
		return False

	for i in range(0, len(chain)):
		if i != len(chain) - 1:
			if chain[i][-1] != chain[i + 1][0]:
				return False
		else:
			if chain[i][-1] != chain[0][0]:
				return False

	return True


print(is_chain(valid_words))