leetcode3.无重复字符的最长字串

 采用滑动窗口方法

class Solution {
public:int lengthOfLongestSubstring(string s) {int n=s.size();if(n==0)return 0;int result=0;unordered_set<char> set;set.insert(s[0]);for(int i=0,j=0;i<n;i++){while(j+1<n&&set.find(s[j+1])==set.end()){set.insert(s[j+1]);j++;}result=max(result,j-i+1);set.erase(s[i]);}return result;}
};