737

737. Sentence Similarity II (Medium)

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.

Return true if sentence1 and sentence2 are similar, or false if they are not similar.

Two sentences are similar if:

• They have the same length (i.e., the same number of words)
• sentence1[i] and sentence2[i] are similar.

Notice that a word is always similar to itself, also notice that the similarity relation is transitive. For example, if the words a and b are similar, and the words b and c are similar, then a and c are similar.

 

Example 1:

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.

Example 2:

Input: sentence1 = ["I","love","leetcode"], sentence2 = ["I","love","onepiece"], similarPairs = [["manga","onepiece"],["platform","anime"],["leetcode","platform"],["anime","manga"]]
Output: true
Explanation: "leetcode" --> "platform" --> "anime" --> "manga" --> "onepiece".
Since "leetcode is similar to "onepiece" and the first two words are the same, the two sentences are similar.

Example 3:

Input: sentence1 = ["I","love","leetcode"], sentence2 = ["I","love","onepiece"], similarPairs = [["manga","hunterXhunter"],["platform","anime"],["leetcode","platform"],["anime","manga"]]
Output: false
Explanation: "leetcode" is not similar to "onepiece".

 

Constraints:

• 1 <= sentence1.length, sentence2.length <= 1000
• 1 <= sentence1[i].length, sentence2[i].length <= 20
• sentence1[i] and sentence2[i] consist of lower-case and upper-case English letters.
• 0 <= similarPairs.length <= 2000
• similarPairs[i].length == 2
• 1 <= xi.length, yi.length <= 20
• xi and yi consist of English letters.

Companies: Uber, Amazon, Google

Related Topics:
Array, Hash Table, String, Depth-First Search, Breadth-First Search, Union Find

Similar Questions:

• Number of Provinces (Medium)
• Accounts Merge (Medium)
• Sentence Similarity (Easy)

Solution 1. Union Find

// OJ: https://leetcode.com/problems/sentence-similarity-ii
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(N)
class UnionFind {
    vector<int> id;
public:
    UnionFind(int n) : id(n) {
        iota(begin(id), end(id), 0);
    }
    int find(int a) {
        return id[a] == a ? a : (id[a] = find(id[a]));
    }
    void connect(int a, int b) {
        id[find(a)] = find(b);
    }
    bool connected(int a, int b) {
        return find(a) == find(b);
    }
};
class Solution {
public:
    bool areSentencesSimilarTwo(vector<string>& A, vector<string>& B, vector<vector<string>>& P) {
        if (A.size() != B.size()) return false;
        unordered_map<string, int> id;
        int index = 0;
        for (auto &s : A) {
            if (id.count(s) == 0) id[s] = index++;
        }
        for (auto &s : B) {
            if (id.count(s) == 0) id[s] = index++;
        }
        UnionFind uf(index);
        for (auto &v : P) uf.connect(id[v[0]], id[v[1]]);
        for (int i = 0; i < A.size(); ++i) {
            if (!uf.connected(id[A[i]], id[B[i]])) return false;
        }
        return true;
    }
};