Dsa
Strings
Medium
Shortest Frequency Window
Find the length of the shortest substring that contains at least K different characters, where each of those characters must appear at least 2 times within that substring. If no such substring exists, print -1.
Example:
Input:
2
aabbcc
Output:
4
(Explanation: 'aabb' has K=2 characters ('a', 'b'), and each appears twice. Length 4. 'bbcc' also works.)
Key concepts
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