Longest Substring Without Repeating Characters
Application of Sliding Window and Two Pointers Technique

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Problem Statement:
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.
Example 4:
Input: s = ""
Output: 0
Solution:
It is very important that get yourself comfortable with Sliding Window technique before solving this problem. I would highly recommend you going through the below problems first, if you haven't done so already:
 Grumpy Bartender
 Longest Substring With Atmost Two Distinct Characters
 Longest Substring With Atmost K Distinct Characters
 Minimum Window Substring
I have discussed the algorithm in the inline comments in the code below.
Java Code:
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Python Code:
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