3. Longest Substring Without Repeating Characters

Given a string s, find the length of the longest substring without repeating characters.

Example 1:

Input: s = "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3.

Example 2:

Input: s = "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.

Example 3:

Input: s = "pwwkew"
Output: 3
Explanation: The answer is "wke", with the length of 3.
Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.

Constraints:

• 0 <= s.length <= 5 * 10^4
• s consists of English letters, digits, symbols and spaces.

Code

C++

class Solution
{
public:
    int lengthOfLongestSubstring(string s)
    {
        int lp = 0;
        int maxLength = 0;
        unordered_set<char> charSet;

        for (int rp = 0; rp < s.length(); rp++)
        {
            while (charSet.find(s[rp]) != charSet.end())
            {
                charSet.erase(s[lp]);
                lp++;
            }

            charSet.insert(s[rp]);
            maxLength = max(maxLength, rp - lp + 1);
        }

        return maxLength;
    }
};