26-CS106X-Practice-Midterm - CS106X Autumn 2010 Handout 26...

CS106X Handout 26
Autumn 2010 October 30 th , 2010
CS106X Practice Midterm
Exam Facts:
When: Wednesday, November 3 rd from 7:00 – 9:00 p.m.
Where: TBA
Note this practice exam is about twice as long as most real midterms.
Coverage
The midterm covers everything up through recursive backtracking, memoization,
searching, sorting, big-oh analysis, pointers, and dynamic memory allocation. I will not
test you on linked lists until the final exam.
We will not be especially picky about syntax or other conceptually shallow ideas. We are
looking for a clear understanding of the core programming concepts in C++.
The exam is open-reader and open-notes, but no computers allowed. Don't let the open-
reader nature mislead you. There isn’t enough time to learn or even re -learn everything
during a two-hour window. You should be experienced enough with the material to
readily answer the questions, relying on your notes only for the occasional detail.
Writing code on paper in a relatively short time period is not quite the same as working
with the compiler and a keyboard. I recommend that you practice writing out solutions to
these practice problems—starting with a blank sheet of paper—until you’re certain you can
write code without a computer to guide you.

Problem 1: Acronyms [courtesy of Julie Zelenski]
An acronym is an abbreviation formed from the first letter of each of a series of words,
such as NATO (North American Treaty Organization) or HTML (Hyper Text Markup
Language). In this problem, you are to write two functions that operate on a table of
acronyms. An acronym data file contains a list of expanded acronyms, one per line, such
as shown here:
American Automobile Association
Internal Revenue Service
Standard Query Language
Parent Teacher Association
Animal Acupuncture Academy
Inertial Reference System
Abdominal Aortic Aneurysm
National Direct Student Loan
The terms within each expansion are separated by at least one and possibly more spaces.
All terms within an expansion are capitalized and thus the acronym formed is uppercase.
a) The ReadIntoMap function reads an acronym data file and builds a map from
acronyms to expansions. The two parameters to the function are a correctly opened
ifstream and an empty map. The function should fill the map with entries where
acronym (e.g. "IRS" ) is the key, and the associated value is its expansion(s) (e.g.,
"Internal Revenue Service" and "Inertial Reference System"). An acronym may
have more than one expansion (e.g., there are three options for "AAA" in the above file)
and thus the value for each key is a vector, where each entry is a possible expansion. A
Scanner will be useful here.
void ReadIntoMap(ifstream& in, Map<Vector<string> >& map) {
b) Although using acronyms can be convenient, it can be confusing when one acronym
has many different expansions. Given a map such as the one created by the function
from part (a), the PercentConfusing function returns the percentage of acronyms in
the map that have more than one expansion. For a map constructed from the data file