思路

利用set 循环滚一边

源码

/** * @param {string} s * @return {number} */var lengthOfLongestSubstring = function(s) {    let len = s.length;    let max = 0;    for(let i = 0; i < len; ++i){        let set = new Set();        for(let j = i; j < len; ++j){            if(set.has(s[j])){                let size = set.size;                max = size > max ? size : max;                break;            }            else{                set.add(s[j]);            }        }        let size = set.size;        max = size > max ? size : max;    }    return max;};复制代码