#+ANKI_DECK: study_deck_02 * TODO 0097. Interleaving String :medium: :PROPERTIES: :NEETCODE: [[file:../../roadmap.org::*0097. Interleaving String][0097. Interleaving String]] :END: 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 ~s~ and ~t~ are divided into ~n~ and ~m~ substrings respectively, such that: - ~s = s_{1} + s_{2} + ... + s_{n}~ - ~t = t_{1} + t_{2} + ... + t_{m}~ - ~|n - m| <= 1~ - The *interleaving* is ~s_{1} + t_{1} + s_{2} + t_{2} + s_{3} + t_{3} + ...~ or ~t_{1} + s_{1} + t_{2} + s_{2} + t_{3} + s_{3} + ...~ *Note:* ~a + b~ is the concatenation of strings ~a~ and ~b~. *Example 1:* #+begin_src Input: s1 = "aabcc", s2 = "dbbca", s3 = "aadbbcbcac" Output: true Explanation: One way to obtain s3 is: Split s1 into s1 = "aa" + "bc" + "c", and s2 into s2 = "dbbc" + "a". Interleaving the two splits, we get "aa" + "dbbc" + "bc" + "a" + "c" = "aadbbcbcac". Since s3 can be obtained by interleaving s1 and s2, we return true. #+end_src *Example 2:* #+begin_src Input: s1 = "aabcc", s2 = "dbbca", s3 = "aadbbbaccc" Output: false Explanation: Notice how it is impossible to interleave s2 with any other string to obtain s3. #+end_src *Example 3:* #+begin_src Input: s1 = "", s2 = "", s3 = "" Output: true #+end_src *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? ** TODO Approach Write your approach here. ** TODO Python #+begin_src python class Solution: def isInterleave(self, s1: str, s2: str, s3: str) -> bool: #+end_src ** TODO C++ #+begin_src cpp class Solution { public: bool isInterleave(string s1, string s2, string s3) { } }; #+end_src