7.cpp

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/* Program extracts from Chapter 7 of
   "Data Structures and Program Design in C++"
   by Robert L. Kruse and Alexander J. Ryba
   Copyright (C) 1999 by Prentice-Hall, Inc.  All rights reserved.
   Extracts from this file may be used in the construction of other programs,
   but this code will not compile or execute as given here. */


// Section 7.1:

typedef int Key;
typedef int Record;


//  Definition of a Key class:
  class Key{
    public:
      //  Add any constructors and methods for key data.
    private:
      //  Add declaration of key data members here.
  };

//  Declare overloaded comparison operators for keys.
  bool operator ==(const Key &x, const Key &y);
  bool operator > (const Key &x, const Key &y);
  bool operator < (const Key &x, const Key &y);
  bool operator >=(const Key &x, const Key &y);
  bool operator <=(const Key &x, const Key &y);
  bool operator !=(const Key &x, const Key &y);

//  Definition of a Record class:
  class Record{
    public:
      operator Key(); //  implicit conversion from Record to Key.
     //  Add any constructors and methods for Record objects.
    private:
     //  Add data components.
  };



// Section 7.2:

Error_code sequential_search(const List<Record> &the_list,
                             const Key &target, int &position)
/*
Post: If an entry in the_list has key equal to target, then return
      success and the output parameter position locates such an entry
      within the list.
      Otherwise return not_present and position becomes invalid.
*/
{
   int s = the_list.size();
   for (position = 0; position < s; position++) {
      Record data;
      the_list.retrieve(position, data);
      if (data == target) return success;
   }
   return not_present;
}


class Key {
   int key;
public:
   static int comparisons;
   Key (int x = 0);
   int the_key() const;
};

bool operator ==(const Key &x,const Key &y);
bool operator >(const Key &x,const Key &y);
bool operator <(const Key &x,const Key &y);
bool operator >=(const Key &x,const Key &y);
bool operator <=(const Key &x,const Key &y);
bool operator !=(const Key &x,const Key &y);


bool operator ==(const Key &x, const Key &y)
{
   Key::comparisons++;
   return x.the_key() == y.the_key();
}


int Key::comparisons = 0;


typedef Key Record;


void test_search(int searches, List<Record> &the_list)
/*

Pre:  None.
Post: The number of key comparisons and CPU time for a
      sequential searching function have been calculated.
Uses: Methods of the classes List, Random, and Timer,
      together with an output function print_out
*/
{
   int list_size = the_list.size();
   if (searches <= 0 || list_size < 0) {
      cout << " Exiting test: " << endl
           << " The number of searches must be positive." << endl
           << " The number of list entries must exceed 0." << endl;
      return;
   }
   int i, target, found_at;
   Key::comparisons = 0;
   Random number;
   Timer clock;

   for (i = 0; i < searches; i++) {
      target = 2 * number.random_integer(0, list_size - 1) + 1;
      if (sequential_search(the_list, target, found_at) == not_present)
         cout << "Error: Failed to find expected target " << target << endl;
   }
   print_out("Successful", clock.elapsed_time(), Key::comparisons, searches);

   Key::comparisons = 0;
   clock.reset();
   for (i = 0; i < searches; i++) {
      target = 2 * number.random_integer(0, list_size);
      if (sequential_search(the_list, target, found_at) == success)
         cout << "Error: Found unexpected target " << target
              << " at " << found_at << endl;
   }
   print_out("Unsuccessful", clock.elapsed_time(), Key::comparisons, searches);
}



// Section 7.3:

class Ordered_list:public List<Record>{
public:
   Ordered_list();
   Error_code insert(const Record &data);
   Error_code insert(int position, const Record &data);
   Error_code replace(int position, const Record &data);
};


Error_code Ordered_list::insert(const Record &data)
/*
Post: If the Ordered_list is not full, the function succeeds:
      The Record data is inserted into the list, following the
      last entry of the list with a strictly lesser key (or in the
      first list position if no list element has a lesser key).
      Else: the function fails with the diagnostic Error_code overflow.
*/
{
   int s = size();
   int position;
   for (position = 0; position < s; position++) {
      Record list_data;
      retrieve(position, list_data);
      if (data >= list_data) break;
   }
   return List<Record>::insert(position, data);
}


Error_code Ordered_list::insert(int position, const Record &data)
/*
Post: If the Ordered_list is not full, 0 <= position <= n,
      where n is the number of entries in the list,
      and the Record data can be inserted at position in the list,
      without disturbing the list order, then the function succeeds:
      Any entry formerly in position and all later entries have their
      position numbers increased by 1 and data is inserted at position
      of the List.
      Else: the function fails with a diagnostic Error_code.
*/
{
   Record list_data;
   if (position > 0) {
      retrieve(position - 1, list_data);
      if (data < list_data)
         return fail;
   }
   if (position < size()) {
      retrieve(position, list_data);
      if (data > list_data)
         return fail;
   }
   return List<Record>::insert(position, data);
}


Error_code recursive_binary_1(const Ordered_list &the_list, const Key &target,
                              int bottom, int top, int &position)
/*
Pre:  The indices bottom to top define the
      range in the list to search for the target.
Post: If a Record in the range of locations
      from bottom to top in the_list has key equal
      to target, then position locates
      one such entry and a code of success is returned.
      Otherwise, the Error_code of not_present is returned
      and position becomes undefined.
Uses: recursive_binary_1 and methods of the classes List and Record.
*/
{
   Record data;
   if (bottom < top) {              // List has more than one entry.
      int mid = (bottom + top) / 2;
      the_list.retrieve(mid, data);
      if (data < target)  // Reduce to top half of list.
         return recursive_binary_1(the_list, target, mid + 1, top, position);
      else                          // Reduce to bottom half of list.
         return recursive_binary_1(the_list, target, bottom, mid, position);
   }
   else if (top < bottom)
      return not_present;           // List is empty.
   else {                           // List has exactly one entry.
      position = bottom;
      the_list.retrieve(bottom, data);
      if (data == target) return success;
      else return not_present;
   }
}


Error_code run_recursive_binary_1(const Ordered_list &the_list,
                                  const Key &target, int &position)
{
  return recursive_binary_1(the_list, target, 0, the_list.size() - 1, position);
}


Error_code binary_search_1 (const Ordered_list &the_list,
                            const Key &target, int &position)
/*
Post: If a Record in the_list  has Key equal to target, then position locates
      one such entry and a code of success is returned.
      Otherwise, not_present is returned and position is undefined.
Uses: Methods for classes List and Record.
*/
{
   Record data;
   int bottom = 0, top = the_list.size() - 1;

   while (bottom < top) {
      int mid = (bottom + top) / 2;
      the_list.retrieve(mid, data);
      if (data < target)
         bottom = mid + 1;
      else
         top = mid;
   }
   if (top < bottom) return not_present;
   else {
      position = bottom;
      the_list.retrieve(bottom, data);
      if (data == target) return success;
      else return not_present;
   }
}


Error_code recursive_binary_2(const Ordered_list &the_list, const Key &target,
                              int bottom, int top, int &position)
/*
Pre:  The indices bottom to top define the
      range in the list to search for the target.
Post: If a Record in the range from bottom to top in the_list
      has key equal to target, then position locates
      one such entry, and a code of success is returned.
      Otherwise, not_present is returned, and position is undefined.
Uses: recursive_binary_2, together with methods from the classes
      Ordered_list and Record.
*/
{
   Record data;
   if (bottom <= top) {
      int mid = (bottom + top) / 2;
      the_list.retrieve(mid, data);
      if (data == target) {
         position = mid;
         return success;
      }

      else if (data < target)
         return recursive_binary_2(the_list, target, mid + 1, top, position);
      else
         return recursive_binary_2(the_list, target, bottom, mid - 1, position);
   }
   else return not_present;
}


Error_code run_recursive_binary_2(const Ordered_list &the_list,
                                  const Key &target, int &position)
{
  return recursive_binary_2(the_list, target, 0, the_list.size() - 1, position);
}


Error_code binary_search_2(const Ordered_list &the_list,
                           const Key &target, int &position)
/*
Post: If a Record in the_list has key equal to target, then position locates
      one such entry and a code of success is returned.
      Otherwise, not_present is returned and position is undefined.
Uses: Methods for classes Ordered_list and Record.
*/
{
   Record data;
   int bottom = 0, top = the_list.size() - 1;
   while (bottom <= top) {
      position = (bottom + top) / 2;
      the_list.retrieve(position, data);
      if (data == target) return success;
      if (data < target) bottom = position + 1;
      else top = position - 1;
   }
   return not_present;
}

/*************************************************************************/