Given strings `s1`, `s2`, and `s3`, find whether `s3` is formed by an interleaving of `s1` and `s2`.

An interleaving of two strings `s` and `t` is a configuration where they are divided into non-empty substrings such that:

- `s = s1 + s2 + ... + sn`
- `t = t1 + t2 + ... + tm`
- `|n - m| <= 1`
- The interleaving is `s1 + t1 + s2 + t2 + s3 + t3 + ...` or `t1 + s1 + t2 + s2 + t3 + s3 + ...`

Note: `a + b` is the concatenation of strings `a` and `b`.

Example 1:

    Input: s1 = "aabcc", s2 = "dbbca", s3 = "aadbbcbcac"
    Output: true

Example 2:

    Input: s1 = "aabcc", s2 = "dbbca", s3 = "aadbbbaccc"
    Output: false

Example 3:

    Input: s1 = "", s2 = "", s3 = ""
    Output: true

Constraints:

- `0 <= s1.length, s2.length <= 100`
- `0 <= s3.length <= 200`
- `s1`, `s2`, and `s3` consist of lowercase English letters.

Follow up: Could you solve it using only `O(s2.length)` additional memory space?