longest-substring-without-repeating-characters

class Solution { public: int lengthOfLongestSubstring(string s) { unordered_set<char> record; int ans = 0; int n = s.size(); int rpointer = -1; for(int i = 0; i < n; ++i) { if(i > 0) { record.erase(s[i-1]); } while(rpointer + 1 < n && (!record.count(s[rpointer + 1]))) { ++rpointer; record.insert(s[rpointer]); } ans = max(ans, rpointer - i + 1); } return ans; } };

class Solution { public: int lengthOfLongestSubstring(string s) { unordered_map<char,int> record; //last time occurred int ans = 0; int n = s.size(); int leftP = 0; int i; for(i = 0; i < n; ++i) { if((record.count(s[i]))) { ans = max(ans, i - leftP); leftP = max(leftP, record[s[i]] + 1); } record[s[i]] = i; } return max(ans, i - leftP); } };