Equal and not equal

Each fact says that two names are equal ("a==b") or not equal ("a!=b"). Equal is what you expect: if a equals b and b equals c, then a equals c. Return True if all the facts can hold at the same time, and False if they contradict each other.

consistent(["a==b", "b==c", "a!=c"])    # False
consistent(["a==b", "c!=a", "c==d"])    # True
consistent(["x!=x"])                    # False

Names are made of the letters a to z and can be longer than one letter, such as "delhi==dilli". There are no spaces.

Some tests join long chains. Write find with a loop, or make sure your trees stay short (lessons 2 and 3): a recursive find on a path of 100,000 nodes stops with RecursionError.

Limits

• Up to 200,000 facts and about 200,000 different names.