Sliding Window problems

Growing and shrinking a window over a sequence to track a running condition.

1. Best Time to Buy and Sell Stock (Easy)
2. Longest Substring Without Repeating Characters (Medium)
3. Longest Repeating Character Replacement (Medium)
4. Permutation in String (Medium)
5. Find All Anagrams in a String (Medium)
6. Minimum Window Substring (Hard)
7. Sliding Window Maximum (Hard)