Check Whether Two Strings are Almost Equivalent

给两个字符串, 问是不是对于每个26个字母, 两个字符串的个数差不多于3个.

class Solution {
    public boolean checkAlmostEquivalent(String word1, String word2) {
        Map<Character, Integer> m1 = new HashMap<>();
        Map<Character, Integer> m2 = new HashMap<>();
        for(char c : word1.toCharArray())
            m1.put(c, m1.getOrDefault(c, 0) + 1);
        for(char c : word2.toCharArray())
            m2.put(c, m2.getOrDefault(c, 0) + 1);
        int res = 0;
        for(int i = 0; i < 26; i++) {
            char c = (char)('a' + i);
            int f1 = m1.getOrDefault(c, 0);
            int f2 = m2.getOrDefault(c, 0);
            if(Math.abs(f1 - f2) > 3)
                return false;
        }
        return true;
    }
}