class Solution {
public:
int lengthOfLongestSubstring(string s) {
set<char> set;
int len = 0;
int lo = 0;
int hi = 0;
while(hi < s.length()){
if(set.find(s[hi]) == set.end()){
set.insert(s[hi]);
}else{
set.clear();
lo = hi;
len = max(len, hi - lo + 1);
hi++;
}
}
return len;
}
};
用set。