LeetCode 3: Longest Substring Without Repeating Characters (Sliding Window Python Solution)
LeetCode 3: Longest Substring Without Repeating Characters explained step by step.
In this video, you’ll learn how to solve the Longest Substring Without Repeating Characters problem using the sliding window technique. This is one of the most important patterns in LeetCode and frequently appears in coding interviews.
We cover 3 different approaches:
Brute force solution
Optimized HashSet approach
Sliding Window technique (most efficient)
You’ll understand:
How to track characters efficiently
How to move the window correctly
Why sliding window reduces time complexity
Clean Python implementation
This is a must-know problem if you want to master string problems and sliding window patterns.
🔍 Keywords:
longest substring without repeating characters solution
leetcode 3 python solution
sliding window explained
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string algorithm sliding window
If you're preparing for coding interviews or practicing LeetCode, this video will help you deeply understand one of the most important algorithm patterns.
#leetcode #slidingwindow #python #algorithms #codinginterview #strings
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https://leetcode.com/problems/longest...
⭐️ Update the video
At 2:13 I say index number usually starts from 0. But right reason to add + 1 is that the difference R - L represents the number of positions between the two indices, not the number of elements including both ends. To correctly count all characters from L to R, including both endpoints, we need to add 1. This ensures the length includes both the starting and ending characters.
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■ Timeline
0:05 Explain a basic idea
0:45 Explain the first approach with sliding window and set
10:19 Coding with sliding window and set
11:40 Time Complexity and Space Complexity with sliding window and set
12:22 Explain the second approach with sliding window and hashing
17:51 Coding with sliding window and hashing
19:19 Time Complexity and Space Complexity with sliding window and hashing
19:30 Explain the third approach with the last position
23:12 Coding with the last position approach
24:24 Time Complexity and Space Complexity with the last position approach
■ Blind 75 LeetCode questions
• Blind 75 LeetCode Questions
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■ Problem Link
https://leetcode.com/problems/longest...
■ Codes in the video
Python, JavaScript, Java and C++ are available from here.
https://leetcode.com/problems/longest...
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#leetcode #python #interview
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