0097. Interleaving String

https://leetcode.com/problems/interleaving-string

Description

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?

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