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is_subsequence

Language/Type: PHP recursion string return

Write a recursive function named is_subsequence that accepts two string parameters, and returns if the second string is a subsequence of the first string. A string is a subsequence of another if it contains the same letters in the same order, but not necessary consecutively. You can assume both strings are already lowercased.

Constraints:

  • Do not declare any global variables or any auxiliary data structures.
  • Do not use any loops; you must use recursion.
Function: Write a PHP function as described, not a complete program.

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