# Minimum Window Substring

Given strings s and t, find the smallest substring of s that contains all characters of t. You expand the right pointer until you have a valid window, then shrink from the left as much as possible while keeping it valid. This is one of the hardest sliding window problems and teaches you to manage a character frequency map as the window changes.

Visit the following resources to learn more:

- [@article@Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring/)
- [@video@Leetcode - Minimum Window Substring (Python)](https://www.youtube.com/watch?v=CX6_L9GLldU)
- [@video@L12. Minimum Window Substring](https://www.youtube.com/watch?v=WJaij9ffOIY)