sentence-similarity.py

# Time:  O(n + p)
# Space: O(p)

# Given two sentences words1, words2 (each represented as an array of strings),
# and a list of similar word pairs pairs, determine if two sentences are similar.
#
# For example, "great acting skills" and "fine drama talent" are similar,
# if the similar word pairs are pairs = [["great", "fine"], ["acting","drama"], ["skills","talent"]].
#
# Note that the similarity relation is not transitive.
# For example, if "great" and "fine" are similar, and "fine" and "good" are similar,
# "great" and "good" are not necessarily similar.
#
# However, similarity is symmetric.
# For example, "great" and "fine" being similar is the same as "fine" and "great" being similar.
#
# Also, a word is always similar with itself.
# For example, the sentences words1 = ["great"], words2 = ["great"], pairs = [] are similar,
# even though there are no specified similar word pairs.
#
# Finally, sentences can only be similar if they have the same number of words.
# So a sentence like words1 = ["great"] can never be similar to words2 = ["doubleplus","good"].
#
# Note:
# - The length of words1 and words2 will not exceed 1000.
# - The length of pairs will not exceed 2000.
# - The length of each pairs[i] will be 2.
# - The length of each words[i] and pairs[i][j] will be in the range [1, 20].

class Solution(object):
    def areSentencesSimilar(self, words1, words2, pairs):
        """
        :type words1: List[str]
        :type words2: List[str]
        :type pairs: List[List[str]]
        :rtype: bool
        """
        if len(words1) != len(words2): return False
        lookup = set(map(tuple, pairs))
        return all(w1 == w2 or (w1, w2) in lookup or (w2, w1) in lookup \
                   for w1, w2 in itertools.izip(words1, words2))