Solution: Minimum Window Subsequence

Explore how to identify the shortest substring of one string containing another as a subsequence using the sliding window technique. This lesson guides you through a step-by-step solution involving forward and backward scanning pointers, enabling you to optimize subsequence matching efficiently. Understand the time and space complexity implications and apply this method to solve related coding interview problems effectively.

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Statement
Solution
- Naive approach
- Optimized approach using sliding window

Statement

Given two strings, s1 and s2, find and return the shortest substring of s1 in which all the characters of s2 appear in the same order, but not necessarily next to each other (i.e., s2 should be a subsequence of the substring).

If no such substring exists, return an empty string "". If there are multiple shortest substrings, return the one that appears first in s1 (i.e., with the left-most starting index).

Note: A substring is a contiguous sequence of characters within a string. A subsequence is a sequence of characters that can be derived from a string by deleting some characters without changing the order of the remaining characters. For example, “edu” is a substring and “cave” is a subsequence of “educative.”

Constraints:

$1 \leq$ s1.length $\leq 2 \times 10^{3}$
$1 \leq$ s2.length $\leq 100$ ...