Find longest subsequence of x that is a substring of y

Given two strings `x` and `y`, compute the **maximum length** of a string `s` such that: - `s` is a **subsequence** of `x` (can delete zero or more characters from `x` without reordering the remaining characters), and - `s` is a **substring** of `y` (must appear as a contiguous block in `y`). Return the maximum possible length. ### Example - `x = "abcd"`, `y = "abdc"` - One optimal choice is `"abd"` (subsequence of `x`, substring of `y`), so the answer is `3`. ### Sample - `x = "hackerranks"`, `y = "hackers"` - Output: `7` (because `"hackers"` is a subsequence of `x` and also a substring of `y`).