{"id":910,"date":"2025-08-20T12:28:16","date_gmt":"2025-08-20T06:58:16","guid":{"rendered":"https:\/\/codeanddebug.in\/blog\/?p=910"},"modified":"2025-08-20T12:28:17","modified_gmt":"2025-08-20T06:58:17","slug":"longest-substring-without-repeating-characters","status":"publish","type":"post","link":"https:\/\/codeanddebug.in\/blog\/longest-substring-without-repeating-characters\/","title":{"rendered":"Longest Substring Without Repeating Characters | Leetcode 3 | Optimal Sliding Window Solution"},"content":{"rendered":"\n

The problem\u00a0\u201cLongest Substring Without Repeating Characters\u201d<\/strong>\u00a0asks for the length of the\u00a0longest substring<\/strong>\u00a0in a string\u00a0s<\/code>\u00a0that contains\u00a0no duplicate characters<\/strong>. A straightforward\u00a0brute force<\/strong>\u00a0approach checks all substrings, while the\u00a0optimal<\/strong>\u00a0solution uses a\u00a0sliding window<\/strong>\u00a0with a\u00a0hash map<\/strong>\u00a0to achieve linear time.<\/p>\n\n\n\n

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Given a string s<\/code>, find the length of the longest<\/strong> substring<\/strong> without duplicate characters.<\/p>\n\n\n\n

Here’s the [Problem Link<\/span><\/mark><\/a><\/strong>] to begin with.<\/p>\n\n\n\n

Example 1:<\/strong><\/p>\n\n\n\n

Input:<\/strong> s = \"abcabcbb\"
Output:<\/strong> 3
Explanation:<\/strong> The answer is \"abc\", with the length of 3.<\/pre>\n\n\n\n
Example 2:<\/strong><\/p>\n\n\n\n
Input:<\/strong> s = \"bbbbb\"
Output:<\/strong> 1
Explanation:<\/strong> The answer is \"b\", with the length of 1.<\/pre>\n\n\n\n
Example 3:<\/strong><\/p>\n\n\n\n
Input:<\/strong> s = \"pwwkew\"
Output:<\/strong> 3
Explanation:<\/strong> 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.<\/pre>\n\n\n\n
Constraints:<\/strong><\/p>\n\n\n\n