class Teste {
 
    public static int seuComparador(String a, String b) {
        int sa = a.length();
        int sb = b.length();
        if (sa == sb) return a.compareTo(b);
        int dif = sa > sb ? sa - sb : sb - sa;
 
        StringBuilder pad = new StringBuilder(sa > sb ? sa : sb);
        for (int i = 0; i < dif; i++) {
            pad.append('0');
        }
 
        String c = sa > sb ? a : pad.append(a).toString();
        String d = sa > sb ? pad.append(b).toString() : b;
        return c.compareTo(d);
    }
 
    public static void main(String[] args) {
        System.out.println(seuComparador("0", "3"));
        System.out.println(seuComparador("10", "3"));
        System.out.println(seuComparador("007", "300"));
        System.out.println(seuComparador("40", "040"));
    }
}

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