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ALG7.CPP
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1997-05-06
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/**************************************************************************
*
* alg7.cpp - Illustrate the use of the sort related generic algorithms.
* Section 13
*
* $Id: alg7.cpp,v 1.2 1995/08/29 18:43:42 oberg Exp $
*
* $$RW_INSERT_HEADER "slyrs.cpp"
*
**************************************************************************/
# include <vector>
# include <deque>
# include <list>
# include <algorithm>
# include <iostream.h>
using namespace std;
int randomInteger(unsigned int n)
{ return rand() % n; }
int randomValue() { return randomInteger(100); }
ostream_iterator<int> intOut (cout, " ");
void sortExample() {
cout << "Sort algorithms" << endl;
// fill both a vector and a deque
// with random integers
vector<int> aVec(15);
deque<int> aDec(15);
generate (aVec.begin(), aVec.end(), randomValue);
generate (aDec.begin(), aDec.end(), randomValue);
// sort the vector ascending
sort (aVec.begin(), aVec.end());
copy (aVec.begin(), aVec.end(), intOut);
cout << endl;
// sort the deque descending
sort (aDec.begin(), aDec.end(), greater<int>() );
copy (aDec.begin(), aDec.end(), intOut);
cout << endl;
// sort the vector descending?
sort (aVec.rbegin(), aVec.rend());
copy (aVec.begin(), aVec.end(), intOut);
cout << endl;
}
void partial_sort_example() {
cout << "Partial sort examples" << endl;
// make a vector of 15 random integers
vector<int> aVec(15);
generate (aVec.begin(), aVec.end(), randomValue);
copy (aVec.begin(), aVec.end(), intOut);
cout << endl;
// partial sort the first seven positions
partial_sort (aVec.begin(), aVec.begin() + 7, aVec.end());
copy (aVec.begin(), aVec.end(), intOut);
cout << endl;
// make a list of random integers
list<int> aList(15, 0);
generate (aList.begin(), aList.end(), randomValue);
copy (aList.begin(), aList.end(), intOut);
cout << endl;
// sort only the first seven elements
vector<int> start(7);
partial_sort_copy (aList.begin(), aList.end(),
start.begin(), start.end(), greater<int>());
copy (start.begin(), start.end(), intOut);
cout << endl;
}
void nth_element_example()
// illustrate the use of the nth_largest function
{
cout << "Nth largest example" << endl;
// make a vector of random integers
vector<int> aVec(10);
generate (aVec.begin(), aVec.end(), randomValue);
// now find the 5th largest
vector<int>::iterator nth = aVec.begin() + 4;
nth_element(aVec.begin(), nth, aVec.end());
cout << "fifth largest is " << *nth << " in" << endl;
copy (aVec.begin(), aVec.end(), intOut);
cout << endl;
}
void binary_search_example ()
// illustrate the use of the binary search functions
{
cout << "Binary search example" << endl;
// make an ordered vector of 15 random integers
vector<int> aVec(15);
generate (aVec.begin(), aVec.end(), randomValue);
sort (aVec.begin(), aVec.end());
copy (aVec.begin(), aVec.end(), intOut), cout << endl;
// see if it contains an eleven
if (binary_search(aVec.begin(), aVec.end(), 11))
cout << "contains an 11" << endl;
else
cout << "does not contain an 11" << endl;
// insert an 11 and a 14
vector<int>::iterator where;
where = lower_bound (aVec.begin(), aVec.end(), 11);
aVec.insert (where, 11);
where = upper_bound (aVec.begin(), aVec.end(), 14);
aVec.insert (where, 14);
copy (aVec.begin(), aVec.end(), intOut), cout << endl;
}
void merge_example ()
// illustrate the use of the merge function
{
cout << "Merge algorithm examples" << endl;
// make a list and vector of 10 random integers
vector<int> aVec(10);
list<int> aList(10, 0);
generate (aVec.begin(), aVec.end(), randomValue);
sort (aVec.begin(), aVec.end());
generate_n (aList.begin(), 10, randomValue);
aList.sort();
// merge into a vector
vector<int> vResult (aVec.size() + aList.size());
merge (aVec.begin(), aVec.end(), aList.begin(), aList.end(),
vResult.begin());
// merge into a list
list<int> lResult;
merge (aVec.begin(), aVec.end(), aList.begin(), aList.end(),
inserter(lResult, lResult.begin()));
// merge into the output
merge (aVec.begin(), aVec.end(), aList.begin(), aList.end(),
ostream_iterator<int> (cout, " "));
cout << endl;
}
class iotaGen {
public:
iotaGen (int c = 0) : current(c) { }
int operator () () { return current++; }
private:
int current;
};
void set_example ()
// illustrate the use of the generic set functions
{
cout << "Set operations:" << endl;
// make a couple of ordered lists
list <int> listOne, listTwo;
generate_n (inserter(listOne, listOne.begin()), 5, iotaGen(1));
generate_n (inserter(listTwo, listTwo.begin()), 5, iotaGen(3));
// now do the set operations
// union - 1 2 3 4 5 6 7
set_union (listOne.begin(), listOne.end(),
listTwo.begin(), listTwo.end(), intOut), cout << endl;
// merge - 1 2 3 3 4 4 5 5 6 7
merge (listOne.begin(), listOne.end(),
listTwo.begin(), listTwo.end(), intOut), cout << endl;
// intersection 3 4 5
set_intersection (listOne.begin(), listOne.end(),
listTwo.begin(), listTwo.end(), intOut), cout << endl;
// difference 1 2
set_difference (listOne.begin(), listOne.end(),
listTwo.begin(), listTwo.end(), intOut), cout << endl;
// symmetric difference 1 2 6 7
set_symmetric_difference (listOne.begin(), listOne.end(),
listTwo.begin(), listTwo.end(), intOut), cout << endl;
if (includes(listOne.begin(), listOne.end(),
listTwo.begin(), listTwo.end()))
cout << "set is subset" << endl;
else
cout << "set is not subset" << endl;
}
void heap_example ()
// illustrate the use of the heap functions
{
ostream_iterator<int> intOut (cout, " ");
// make a heap of 15 random integers
vector<int> aVec(15);
generate (aVec.begin(), aVec.end(), randomValue);
make_heap (aVec.begin(), aVec.end());
copy (aVec.begin(), aVec.end(), intOut), cout << endl;
cout << "Largest value " << aVec.front() << endl;
// remove largest and reheap
pop_heap(aVec.begin(), aVec.end());
aVec.pop_back();
copy (aVec.begin(), aVec.end(), intOut), cout << endl;
// add a 97 to the heap
aVec.push_back(97);
push_heap (aVec.begin(), aVec.end());
copy (aVec.begin(), aVec.end(), intOut), cout << endl;
// finally, make into sorted collection
sort_heap (aVec.begin(), aVec.end());
copy (aVec.begin(), aVec.end(), intOut), cout << endl;
}
int main() {
cout << "Sorting generic algorithms examples" << endl;
sortExample();
partial_sort_example();
nth_element_example();
binary_search_example();
merge_example();
set_example();
heap_example();
cout << "End sorting examples" << endl;
return 0;
}