Sentence Similarity II — LeetCode 737 Python Solution

The problem

We can represent a sentence as an array of words, for example, the sentence "I am happy with leetcode" can be represented as arr = ["I","am",happy","with","leetcode"]. Given two sentences sentence1 and sentence2 each represented as a string array and given an array of string pairs similarPairs where similarPairs[i] = [xi, yi] indicates that the two words xi and yi are similar.

Example

Input

sentence1 = ["great","acting","skills"], sentence2 = ["fine","drama","talent"], similarPairs = [["great","good"],["fine","good"],["drama","acting"],["skills","talent"]]

Output

true

Explanation

The two sentences have the same length and each word i of sentence1 is also similar to the corresponding word in sentence2.

Python solution

class Solution:
    def areSentencesSimilarTwo(
        self, sentence1: List[str], sentence2: List[str], similarPairs: List[List[str]]
    ) -> bool:
        if len(sentence1) != len(sentence2):
            return False
        n = len(similarPairs)
        p = list(range(n << 1))

        def find(x):
            if p[x] != x:
                p[x] = find(p[x])
            return p[x]

        words = {}
        idx = 0
        for a, b in similarPairs:
            if a not in words:
                words[a] = idx
                idx += 1
            if b not in words:
                words[b] = idx
                idx += 1
            p[find(words[a])] = find(words[b])

        for i in range(len(sentence1)):
            if sentence1[i] == sentence2[i]:
                continue
            if (
                sentence1[i] not in words
                or sentence2[i] not in words
                or find(words[sentence1[i]]) != find(words[sentence2[i]])
            ):
                return False
        return True

Complexity

Pattern: Union-Find

Merge groups and ask whether two things are connected, both in near-constant time. LeetCode 737. Sentence Similarity II is filed here because LeetCode tags it Union Find, which is the vocabulary this hub collects.

The union-find guide has the Python template for the pattern and the 83 LeetCode problems that use it.

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