Permutation in String- Leetcode 567 - Python

LeetCode 567 – Permutation in String | Sliding Window Explained In this video, we break down one of the most important sliding window problems for coding interviews. Permutation in String Problem Summary Given two strings s1and s2 check if s2 contains a permutation of s1. In simple terms does s2 have any substring that is just a rearrangement of s1? What you’ll learn in this video How to identify sliding window problems Fixed vs Variable window (intuition) Using frequency maps efficiently How to optimize from brute force → optimal solution Step-by-step dry run Key Idea Instead of checking all permutations (which is expensive), we maintain a fixed-size window of length len(s1) and compare character frequencies. Time Complexity:** O(n) Topics Covered Sliding Window Pattern HashMap / Frequency Count String Manipulation Why this matters: This pattern is extremely common in interviews (Amazon, Google, Meta). Mastering this will help you solve multiple similar problems quickly. Related Problems to Practice * Longest Substring Without Repeating Characters * Find All Anagrams in a String * Longest Repeating Character Replacement If this helped you, don’t forget to like & subscribe! More daily LeetCode + System Design content coming soon #leetcode #codinginterview #slidingwindow #dsa #softwareengineer #softwareengineering #softwareengineerinterview #sde1 #sde2 #backendengineering