public void MaxRight_aba()
 {
     Assert.AreEqual("ba", MaxNonRepeatCharSubstring.FindMaxRightCrossSubstring("aba", 0, 1, 2));
 }
 public void MaxRight_adbca()
 {
     Assert.AreEqual("dbca", MaxNonRepeatCharSubstring.FindMaxRightCrossSubstring("adbca", 0, 2, 4));
 }