wc-list.cpp (list data structure):

 find/search   O(n)
 insert        O(n) to do the find
 erase         O(n) to do the find


 wc-map.cpp (map data structure):

 find/search   O(log n)
 insert        O(log n)
 erase         O(log n)


 For map data structures, we can
  use any key data type, as long as
  there's an ordering defined
   (i.e. operator< must be defined).

 Once a key and its value are entered
  in the map, the key cannot be changed
   (we can erase and re-add).

 There are no duplicate keys.

 Keys "THE" and "the" are different.
 So, to normalize this data, convert
   to lowercase beforehand....

 Maps rely on the pair<> data structure.

 The operator[] function will either
   find the given key/value OR will
   add the given key/value pair.

 If you want to just lookup a key
   without adding it to the map,
   the operator[] is NOT going to
   work....it always finds or adds.

 To just lookup a key to see if it's
   there or not, use find():

      words.find( "juniper" );

      returns a map iterator



 map< Student, Grid > m1;

   We can use Student as the key
     as long as we have operator<
     defined on Student.


 map< Student, double > m2;

   Class Student has a vector<double>
     as one of its member variables.

   Student s;
   // ... fills in the name, grades for s

   m2[s] = s.get_gpa();  // add

   // ... change grades for s

   m2[s] = s.get_gpa();  // update