LeetCode – Refresh – Longest Substring Without Repeating Characters

For this problem, we are OK to use hash set, since no numbers are needed.

 

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        int len = s.size(), result = 0;
        if (len < 2) return len;
        unordered_set<char> sets;
        for (int left = 0, right = 0; right < len; right++) {
            if (sets.find(s[right]) == sets.end()) {
                result = max(result, right - left + 1);
                sets.insert(s[right]);
            } else {
                sets.erase(s[left++]);
                right--;
            }
        }
        return result;
    }
};