class Solution {
    public int longestStrChain(String[] words) {
        Arrays.sort(words, (s1, s2) -> s1.length() - s2.length());
        int ans = 0;
        Map<String, Integer> wordsMap = new HashMap();
        for (String word : words) {
            int maxLen = 0;
            for (int j = 0; j < word.length(); j++) {
                String s = word.substring(0, j) + word.substring(j+1);
                maxLen = Math.max(maxLen, wordsMap.getOrDefault(s, 0) + 1);
            }
            wordsMap.put(word, maxLen);
            ans = ans < maxLen ? maxLen : ans;
        }
        return ans;
    }
}