Solution.java

class Solution {
    private int[] p;

    public boolean areSentencesSimilarTwo(
        String[] sentence1, String[] sentence2, List<List<String>> similarPairs) {
        if (sentence1.length != sentence2.length) {
            return false;
        }
        int n = similarPairs.size();
        p = new int[n << 1];
        for (int i = 0; i < p.length; ++i) {
            p[i] = i;
        }
        Map<String, Integer> words = new HashMap<>();
        int idx = 0;
        for (List<String> e : similarPairs) {
            String a = e.get(0), b = e.get(1);
            if (!words.containsKey(a)) {
                words.put(a, idx++);
            }
            if (!words.containsKey(b)) {
                words.put(b, idx++);
            }
            p[find(words.get(a))] = find(words.get(b));
        }
        for (int i = 0; i < sentence1.length; ++i) {
            if (Objects.equals(sentence1[i], sentence2[i])) {
                continue;
            }
            if (!words.containsKey(sentence1[i]) || !words.containsKey(sentence2[i])
                || find(words.get(sentence1[i])) != find(words.get(sentence2[i]))) {
                return false;
            }
        }
        return true;
    }

    private int find(int x) {
        if (p[x] != x) {
            p[x] = find(p[x]);
        }
        return p[x];
    }
}