Given two strings s and t, return the length of the longest prefix of s that is a subsequence of t (characters of t may be skipped but not reordered).
Examples
Input: s = "abc", t = "acb"
Output: 2
Explanation: "ab" is a subsequence of "acb" but "abc" is not.
Input: s = "axc", t = "abcxc"
Output: 3
Constraints
0 <= len(s), len(t) <= 10**5- Target: O(len(t)) time, O(1) extra space.
Goals
- Advance one pointer only on a match and the other unconditionally
- Read the answer off the pointer position at the end