Remove substrings inside a list with better than O(n^2) complexity

Question

I have a list with many words (100.000+), and what I\'d like to do is remove all the substrings of every word in the list.

So for simplicity, let\'s imagine that I have

Answer 1

Build the set of all (unique) substrings first, then filter the words with it:

def substrings(s):
    length = len(s)
    return {s[i:j + 1] for i in range(length) for j in range(i, length)} - {s}


def remove_substrings(words):
    subs = set()
    for word in words:
        subs |= substrings(word)

    return set(w for w in words if w not in subs)