Combine String

For this question, we give you 3 strings and we ask if it is possible to make the 3rd string by merging the 2 other strings. What we mean by merging is that we can cut up both strings into a series of substrings that can be combined to form a 3rd string. The relative order in which characters appear in the first 2 strings must be maintained. Furthermore, you cannot take parts of the first 2 strings to make the 3rd string, all characters must be used when merging.


  • s1: First string
  • s2: Second string
  • s3: Target string that the other 2 strings must be combined to make


Whether or not the 3rd string can be made


Example 1:


1s1 = abe
2s2 = cdf
3s3 = abcdef

Output: true


We can make abcdef by doing ab + cd + e + f = abcdef

Example 2:


1s1 = abe
2s2 = cdf
3s3 = abcd

Output: false


We cannot use parts of the first 2 strings as stated in the problem description so therefore this is not possible.


  • 1 <= s1.length, s2.length, s3.length <= 500

Try it yourself




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1  >>> a = [1, 2, 3]
2  >>> a[-1]
3  3

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