Question

Bet you can't figure this out

Create a Recursive Method to test whether a partial string is a subset of a full string. If the partial string is a subset of the full string return true. Otherwise return false.Create a Recursive Method to test whether a partial string is a subset of a full string. If the partial string is a subset of the full string return true. Otherwise return false.

Here is the Main and Recursive below: (Note only need the Recursive)

Main:

public class Chapter13Main {

   public static void main(String[] args) {
       RecursiveContains rc = new RecursiveContains();
       System.out.println(rc.contains_recursive("xd", "thurtle")); // False

       System.out.println(rc.contains_recursive("th", "thurtle")); // True

       System.out.println(rc.contains_recursive("trl", "thurtle")); // True

       System.out.println(rc.contains_recursive("utl", "thurtle")); // True

       // Strings are case sensitive
       System.out.println(rc.contains_recursive("Tr", "thurtle")); // False
   }

}

Recursive:

public class RecursiveContains {

   /**
   * This method tests whether the first String the "partial" is a substring of
   * the "full" string. If the partial string contains all of the characters of
   * the full string in the same order return true. Else return false. Example:
   * "tbl" "table" => true tbl appears in that order in both strings
   *
   * "tlb" "table" => false tlb does not appear in that order in the full string.
   *
   */
   public boolean contains_recursive(String partial, String full) {
       return false;
   }

}

Answer 1

public class RecursiveContains {

    /**
     * This method tests whether the first String the "partial" is a substring of
     * the "full" string. If the partial string contains all of the characters of
     * the full string in the same order return true. Else return false. Example:
     * "tbl" "table" => true tbl appears in that order in both strings
     * <p>
     * "tlb" "table" => false tlb does not appear in that order in the full string.
     */
    public boolean contains_recursive(String partial, String full) {
        if (partial.isEmpty()) {
            return true;
        } else if (full.isEmpty()) {
            return false;
        } else {
            return (full.charAt(0) == partial.charAt(0) && contains_recursive(partial.substring(1), full.substring(1)))
                    || contains_recursive(partial, full.substring(1));
        }
    }

}

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