15-100 Sections U-V-AA / Spring 2009 / Quiz 3
20 Minutes


Note:  On this quiz, you may only use/call methods that you write yourself (so no Math methods, String methods, etc), except for print(), println(), charAt(), and length() (which you may use).

Also note:  on this quiz, you may use loops or conditionals.

  1. oneEdit
    Write a method named “oneEdit” that takes two strings and returns true if the first string can be transformed into the second string with exactly one single edit, and false otherwise (or if either string is null), where an edit is any one of these three operations:
       * Insert a single character  (eg, “cat”     à “chat”)
       * Delete a single character (eg, “smile”     à “mile”)
       * Swap a single character (eg, “cubs”     à “cabs”)

    Note that the new character in a swap must differ from the character being swapped out, so in particular a string cannot be transformed into itself in one edit.

    Write three well-chosen helper methods, one for each type of edit (insert, delete, swap), and write a suitable test method (a single test method for all cases).  Along with “oneEdit”, that makes five methods, each worth 20% of the quiz grade.

  2. Bonus/Optional:  eToTheX
    Based on the Maclaurin series expansion of ex, we know that:

    Using this fact, and not using any Math methods or Math constants, write a method named eToTheX that takes a double value x and returns ex to some reasonable degree of accuracy.  Write well-chosen helper methods, both for simplicity and for partial credit.