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 * 104
• s consists of English letters, digits, symbols and spaces.

BruteForce §

 
    int lengthOfLongestSubstring(string s) {
 
    int max = 0;
    for (int i = 0; i<s.length(); i++){
        vector<bool> distinct(256);
        for (int j = i; j < s.length(); j++ ){
            if (!distinct[s[j]]){
                int l = j - i + 1;
                max < l ? max = l : max=max;
                distinct[s[j]] = true;
            } 
            else {
                break;
                }
        }
    }
    cout << max;
 
    return max;
 
    }