Practice/Meta/Leetcode 3. Longest Substring Without Repeating Characters

Leetcode 3. Longest Substring Without Repeating Characters

CodingMust

Problem

Given a string, determine the length of the longest contiguous substring that contains all unique characters (no character appears more than once within that substring).

You need to find the maximum length among all possible substrings where every character appears at most once.

Requirements

1. Return an integer representing the length of the longest valid substring
2. The substring must be contiguous (characters must appear consecutively in the original string)
3. Each character in the valid substring must be unique
4. If the input string is empty, return 0

Constraints

• 0 ≤ s.length ≤ 50,000
• The string consists of English letters, digits, symbols, and spaces
• Target time complexity: O(n) where n is the length of the string
• Target space complexity: O(min(m, n)) where m is the character set size

Examples

Example 1:

Input: s = "abcabcbb" Output: 3 Explanation: The longest substring without repeating characters is "abc", which has length 3.

Example 2:

Input: s = "bbbbb" Output: 1 Explanation: The longest substring is "b", with length 1.

Example 3:

Input: s = "pwwkew" Output: 3 Explanation: The longest substring is "wke", with length 3. Note that "pwke" is not valid because it's not a substring (the characters aren't consecutive).

Example 4:

Input: s = "" Output: 0 Explanation: An empty string has no characters.