ByteDance Hard Interview Questions

Background: ByteDance applications often handle large data inputs and require optimized substring searches for algorithms that analyze user data patterns. The need for efficient text processing arises, especially in content recommendation systems.
Problem statement: Given a string s and a string t, return the minimum window substring of s such that every character in t (including duplicates) is included in the window. If there is no such substring, return an empty string. You must optimize for performance due to potentially large inputs.
Function/class signature:

• def min_window(s: str, t: str) -> str:

Example 1:

• Input: s = "ADOBECODEBANC", t = "ABC"


• Output: "BANC"


• Explanation: The minimum window substring is "BANC" which contains all characters of "ABC".

Example 2:

• Input: s = "AA", t = "AA"


• Output: "AA"


• Explanation: The whole string is the minimum window which contains all of t.

Constraints:

• 1 <= len(s), len(t) <= 1000


• s and t consist of English letters.