734. Sentence Similarity

/**
 * Time Complexity: O(N + P) Space Complexity : O(P)
 *
 * N = length of words1. P = size of pairs.
 */
class Solution {
    public boolean areSentencesSimilar(String[] words1, String[] words2, String[][] pairs) {
        if (words1 == null || words2 == null || words1.length != words2.length) {
            return false;
        }

        Map<String, Set<String>> pairsMap = new HashMap();
        for (String[] pair : pairs) {
            if (!pairsMap.containsKey(pair[0])) {
                pairsMap.put(pair[0], new HashSet<String>());
            }
            if (!pairsMap.containsKey(pair[1])) {
                pairsMap.put(pair[1], new HashSet<String>());
            }
            pairsMap.get(pair[0]).add(pair[1]);
            pairsMap.get(pair[1]).add(pair[0]);
        }

        for (int i = 0; i < words1.length; i++) {
            if (words1[i].equals(words2[i])) {
                continue;
            }
            if (!pairsMap.containsKey(words1[i])) {
                return false;
            }
            if (!pairsMap.get(words1[i]).contains(words2[i])) {
                return false;
            }
        }

        return true;
    }
}