737. Sentence Similarity II (use hashmap version)

```java
class Solution {
    public boolean areSentencesSimilarTwo(String[] sentence1, String[] sentence2, List<List<String>> similarPairs) {
        if (sentence1.length != sentence2.length) {
            return false;
        }

        UnionFind uf = new UnionFind(sentence1, sentence2);

        for (List<String> pair : similarPairs) {
            uf.union(pair.get(0), pair.get(1));
        }
        for (int i = 0; i < sentence1.length; i++) {
            String rootX = uf.find(sentence1[i]);
            String rootY = uf.find(sentence2[i]);
            if (!rootX.equals(rootY)) {
                return false;
            }
        }
        return true;
    }
    class UnionFind {
        private Map<String, String> parent;
        UnionFind(String[] sentence1, String[] sentence2) {
            this.parent = new HashMap<>();
            init(sentence1);
            init(sentence2);
        }
        public void init(String[] sentence) {
            for (int i = 0; i < sentence.length; i++) {
                if (parent.containsKey(sentence[i])) {
                    return;
                }
                parent.put(sentence[i], sentence[i]);
            }
        }
        public String find(String x) {
            if (parent.containsKey(x) && parent.get(x) != x) {
                parent.put(x, find(parent.get(x)));
            }
            return parent.get(x) == null ? x : parent.get(x);
        }
        public void union(String x, String y) {
            String rootX = find(x);
            String rootY = find(y);
            if (rootX != rootY) {
                parent.put(rootX, rootY);
            }
        }
    }
}

/*
use union find

1. union first

2. then use find to check similarity



[["great","good"],["fine","good"],["drama","acting"],["skills","talent"]]

"great","good","fine"


drama","acting"
"skills","talent"
*/
```ja