领扣 无重复字符的最长子串

 1 /**
 2 * @param {string} s
 3 * @return {number}
 4 */
 5 var lengthOfLongestSubstring = function(s) {
 6   if (s == '') return 0;
 7   let str ='',long=0,temp=0;
 8   for (let i =0;i<s.length;i++){
 9      if (str.indexOf(s[i])== -1){
10         str += s[i];
11         temp++;
12      } else {
13        long = long > temp ? long : temp;
14        str = str.substring(str.indexOf(s[i])+1) + s[i];  //从重复的字符截取
15        temp =str.length;
16      }
17   }
18   long = long > temp ? long : temp;
19   return long;
20 };