Given two strings *s* and *t*, return the minimum window substring of *s* such that every character of *t* (including multiplicity) is included. If there is no such window, return the empty string. If there are multiple answers, you may return any one of them.
s = "text string", t = "target characters"
String (minimum window containing all chars of t)
Example 1:
Input:
s = "ADOBECODEBANC" t = "ABC"
Output:
BANC
Explanation:
"BANC" is the smallest substring containing A, B, and C.
Example 2:
Input:
s = "a" t = "a"
Output:
a
Explanation:
The whole string is the minimum window.