Update README.md

Author: deeksha7chauhan

README.md

@@ -1,7 +1,9 @@
 # NeetCode150Practice
 
 2 pointer approach - Mainly used for reducing our time complexity from Big O(n) to linear n i.e O(n^2) -> O(n)
-Sliding window approach 
+Sliding window approach.
+# Qs.Considering the constraint that s consists of English letters, digits, symbols, and spaces, what is the maximum possible size of our window?
+Ans. In ASCII, there are 95 printable characters: 26 lowercase English letters, 26 uppercase English letters, 10 digits (0-9), 32 special characters and symbols, and the space character. This makes a total of 95 unique characters. Even if you don’t know there are exactly 95, it reasonable that there would be more than 52 (26 uppercase, 26 lowercase).
 
 
 HashSet:- A Set is a data structure that maintains a collection of unique elements. It provides constant-time complexity for search, insertion, and deletion, making it a suitable choice for tracking unique characters in a string.