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.
Example 1:
Input: s = "ADOBECODEBANC", t = "ABC"
Output: "BANC"
Explanation: The minimum window substring "BANC" includes 'A', 'B', and 'C' from string t.
Example 2:
Input: s = "a", t = "a"
Output: "a"
Explanation: The entire string s is the minimum window.
Example 3:
Input: s = "a", t = "aa"
Output: ""
Explanation: Both 'a's from t must be included in the window. Since s only has one 'a', return empty string.
Examples
Example 1
Input: s = "ADOBECODEBANC", t = "ABC"
Output: "BANC"
Explanation: The minimum window substring "BANC" (indices 9-12) contains all characters from t: 'A', 'B', and 'C'.
Example 2
Input: s = "a", t = "a"
Output: "a"
Explanation: The entire string s is the smallest window that contains all characters of t.
Constraints
- -m == s.length
- -n == t.length
- -1 <= m, n <= 10^5
- -s and t consist of uppercase and lowercase English letters.
Optimal Complexity
Time
O(m + n)
Space
O(m + n)
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