LeetCode #76: Minimum Window Substring Python Implementation

LeetCode #76 – Minimum Window Substring | Python Implementation I implemented a sliding window approach with two HashMaps to find the smallest substring containing all characters from t. The countT map stores the required character frequencies, while window tracks the current window's frequencies. Two counters have and need track how many unique characters have met their required counts. The right pointer expands the window until all requirements are satisfied, then the left pointer contracts to minimize the window size while maintaining validity. This pattern is critical in text search engines, log parsers, and bioinformatics for pattern matching in genomic sequences. Key Takeaway: The have vs need tracking elegantly reduces the problem to counting satisfied unique characters rather than checking all frequencies repeatedly. The inner while loop aggressively shrinks the window once valid, ensuring we capture the smallest possible substring before expanding again. Time: O(n + m) where n = len(s), m = len(t) | Space: O(m) #LeetCode #DataStructures #Python #SlidingWindow #HashMap #CodingInterview #ProblemSolving #SoftwareEngineering

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