Longest Substring Without Repeating Characters

The Problem Given a string s, find the length of the longest substring without repeating characters. A substring is a contiguous non-empty sequence of characters within a string. Examples Input: s = "abcabcbb" Output: 3 Explanation: The answer is "abc", with the length of 3. Input: s = "bbbbb" Output: 1 Explanation: The answer is "b", with the length of 1. 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. Brute Force Solution func lengthOfLongestSubstring(_ s: String) -> Int { let n = s.count var res = 0 for i in 0 ..< n { var chars: [Character] = [] for j in i ..< n { if chars.contains(s[j]) { break } chars.append(s[j]) } res = max(res, chars.count) } return res } Explanation Let’s start by visualizing the problem: ...