ThreeCharacters

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class ThreeCharacters {
  public static boolean threeCharMatch(String s, String t) {
    if (s.length() < 3 || t.length() < 3) return true;
    else if (s.length() == 3 && t.length() == 3 && s.equals(t)) return false;
    for (int i = 0; i + 3 <= s.length(); i++) {
      String ss = s.substring(i, i + 3);
      Pattern p = Pattern.compile(Pattern.quote(ss));
      Matcher m = p.matcher(t);
      if (m.find()) return false;
    }
    return true;
  }

  public static void main(String[] args) {
    String a = "a";
    String b = "b";
    System.out.println(a + ", " + b + ": " + threeCharMatch(a, b));
    a = "ab";
    b = "bc";
    System.out.println(a + ", " + b + ": " + threeCharMatch(a, b));
    a = "abc";
    b = "abc";
    System.out.println(a + ", " + b + ": " + threeCharMatch(a, b));
    a = "abcd";
    b = "bcde";
    System.out.println(a + ", " + b + ": " + threeCharMatch(a, b));
    a = "abcd";
    b = "wxyz";
    System.out.println(a + ", " + b + ": " + threeCharMatch(a, b));
  }
}