public class isogram {
    public static boolean  isIsogram(String str) {
        int[] letters = new int['z'- 'a'];
        str = str.toLowerCase();
        for (int i=0; i<str.length(); i++){
          int index = (str.charAt(i)) -'a';
          if (letters[index] == 1){
            return false;
          }
          letters[index]++;
        }
        return true;
    } 
}

@@ -373,8 +373,165 @@
    %7D %0A%7D%0A
+%0Apublic class isogramBest %7B%0A  public static boolean  isIsogram(String str) %7B%0A    return str.length() == str.toLowerCase().chars().distinct().count();%0A  %7D %0A%7D%0A

Update isogram.java