Count Of Substrings With Exactly K Unique Characters
1. You are given a string(str) and a number K. 2. You have to find the count of valid substrings of the given string. 3. Valid substring is defined as a substring that has exactly K unique characters.
1 <= length of string <= 10^5 1 <= k <= 26
A number representing count of substrings with exactly K unique characters.