524. Longest Word in Dictionary through Deleting

class Solution {
    public String findLongestWord(String s, List<String> d) {
        int len = 0, clen = 0;
        String res = "";
        for(String w : d)
        {
            if(lcs(s, w))
            {
                len = w.length();
                if(len >= clen)
                {
                    if(len > clen) res = w;
                    if(len == clen && res.compareTo(w) >= 0)
                        res = w;
                    clen = len;
                }
            }
        }
        return res;
    }

    boolean lcs(String a, String b)
    {
        int m = a.length(), n = b.length(), i = 0, j = 0;
        if(m < n) return false;
        while(i < m && j < n)
        {
            if(a.charAt(i) == b.charAt(j))
            {
                i++;
                j++;
            }
            else i++;
        }
        return j == n;
    }
}