# Minimum Window Substring Given two strings `s` and `t` of lengths `m` and `n` respectively, 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 *the empty string `""`*. The testcases will be generated such that the answer is **unique**. --- ### Examples **Example 1:** ```text Input: s = "ADOBECODEBANC", t = "ABC" Output: "BANC" Explanation: The minimum window substring "BANC" includes 'A', 'B', and 'C' from string t. ``` **Example 2:** ```text Input: s = "a", t = "a" Output: "a" Explanation: The entire string s is the minimum window. ``` --- ### Constraints * `m == s.length` * `n == t.length` * `1 <= m, n <= 10^5` * `s` and `t` consist of uppercase and lowercase English letters.