3 Longest Substring Without Repeating Characters

     public int lengthOfLongestSubstring(String s) {
         long length = s.length();
         String tmp = "";
         int substringLength = 0;
         for (int i = 0; i < length; i ++) {
             if (tmp.contains(("" + s.charAt(i)))) {
                 if (tmp.length() > substringLength)
                     substringLength = tmp.length();
                 int idx = tmp.indexOf(s.charAt(i) + "");
                 tmp = tmp.substring(idx + 1) + s.charAt(i);
             }
             else {
                 tmp = tmp + s.charAt(i);
                 if (substringLength < tmp.length())
                     substringLength = tmp.length();
             }
         }
         return substringLength;
     }