Pattern 2: 4. Medium: Longest Substring Without Repeating Characters

Description: Find the length of the longest substring without repeating characters.

Java

public int lengthOfLongestSubstring(String s)
{ Set<Character> set = new HashSet<>();
int left = 0, maxLength = 0;
for (int right = 0; right < s.length(); right++)
{ while (set.contains(s.charAt(right))) {
set.remove(s.charAt(left));

left++; } set.add(s.charAt(right)); maxLength = Math.max(maxLength, right - left + 1); } return maxLength; } C++: cpp int lengthOfLongestSubstring(string s) { unordered_set set; int left = 0, maxLength = 0; for (int right = 0; right < s.size(); right++) { while (set.count(s[right])) { set.erase(s[left]); left++; } set.insert(s[right]); maxLength = max(maxLength, right - left + 1); } return maxLength; }

Python

def lengthOfLongestSubstring(s):
char_set = set()

left, max_len = 0, 0 for right in range(len(s)): while s[right] in char_set: char_set.remove(s[left]) left += 1 char_set.add(s[right]) max_len = max(max_len, right - left + 1) return max_len