Given two strings s and t, return the shortest substring of s such that every character in t, including duplicates, is present in the substring. If such a substring does not exist, return an empty string "".

You may assume that the correct output is always unique.

Example 1:

Input: s = "OUZODYXAZV", t = "XYZ"

Output: "YXAZ"

Explanation: "YXAZ" is the shortest substring that includes "X", "Y", and "Z" from string t.

Example 2:

Input: s = "xyz", t = "xyz"

Output: "xyz"

Example 3:

Input: s = "x", t = "xy"

Output: ""

Constraints:

• 1 <= s.length <= 100,000
• 1 <= t.length <= 100,000
• s and t consist of uppercase and lowercase English letters.