CSE2050 Spr. 2003 Exam #1, open books, open notes.  Name ___________________

1.  What does the following code print?  (10 pts)

  try {
    cout << 1;
    throw 2;
    cout << 3;
  }
  catch (int x) {
    cout << x;
  }
  catch (...) {
    cout << 4;
  }
  cout << 5;

  // ANSWER: 125

2.  What is the g++ command to compile, but not link, main.cpp? (10 pts)

  // ANSWER: g++ -c main.cpp

3.  Consider a database which associates a list of children with
a parent.  The data is stored in a map<string, vector<string> >, where
the key is the parent's name and the value is a list of children.
Write a function (using the most appropriate form of parameter passing)
that prints the database.  The output should be one line for each
parent, in the form "parent: child child child ...".  The parents should
be listed in alphabetical order.  The children may be printed in any order.
For example: (30 pts)

  map<string, vector<string> > m;
  m["Barbara"].push_back("Sam");
  m["Alice"].push_back("Phil");
  m["Barbara"].push_back("John");
  print(m);  // Alice: Phil
             // Barbara: Sam John

  // ANSWER
  void print(const map<string, vector<string> >& m) {
    for (map<string, vector<string> >::const_iterator p=m.begin(); p!=m.end(); ++p) {
      cout << p->first << ":";
      for (int i=0; i<int(p->second.size()); ++i) // Or use iterators
        cout << " " << p->second[i];
      cout << "\n";  // or endl
    }
  }


4.  Write a function that takes m and returns the average number of children
per parent (as a double).  For example, average(m) would return 1.5 (25 pts).

  // ANSWER
  double average(const map<string, vector<string> >& m) {
    int children=0;
    for (map<string, vector<string> >::const_iterator p=m.begin(); p!=m.end(); ++p)
      children += p->second.size();
    return double(children) / double(m.size());  // beware of int division
  }


5.  Write a function that takes m and the name of a parent and child, and
returns true if that child is a child of the parent.  If the parent is
not listed in m, it should return false.  Use both m.find() and the
find() function in <algorithm>.  For example (25 pts).

  ischildof(m, "Barbara", "Sam");  // true
  ischildof(m, "Sally", "Phil");  // false

  // ANSWER
  bool ischildof(const map<string, vector<string> >& m,
                 const string& parent, const string& child) {
    map<string, vector<string> >::const_iterator p = m.find(parent);
    return p != m.end()
      && find(p->second.begin(), p->second.end(), child) != p->second.end();
  }