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==A priority_queue for integers==

<source lang="cpp">#include <iostream>
#include <string>
#include <queue>
#include <stack>
using namespace std;
int main()
{
priority_queue<int> pq;
cout << "A priority_queue for integers.\n";
pq.push(1);
pq.push(3);
pq.push(4);
pq.push(2);
cout << "retrieve those values in priority order.\n";
while(!pq.empty()) {
cout << "Popping ";
cout << pq.top() << "\n";
pq.pop();
}
cout << endl;

return 0;
}</source>

==A priority_queue with the Smallest Value at the Front Using a Predicate==

<source lang="cpp">#include <queue>
#include <iostream>
int main ()
{
using namespace std;
priority_queue <int, vector <int>, greater <int> > pqIntegers;
pqIntegers.push (10);
pqIntegers.push (5);
pqIntegers.push (-1);
pqIntegers.push (20);
cout << "The queue contains " << pqIntegers.size () << " elements";
cout << endl;
cout << "Element at the top: " << pqIntegers.top () << endl << endl;
while (!pqIntegers.empty ())
{
cout << "pop the topmost element " << pqIntegers.top ();
pqIntegers.pop ();
}
return 0;
}</source>

==Get top() from priority_queue==

<source lang="cpp">#include <iostream>
#include <string>
#include <queue>
#include <stack>
using namespace std;
int main()
{
priority_queue<int> pq;
cout << "A priority_queue for integers.\n";
pq.push(1);
pq.push(3);
pq.push(4);
pq.push(2);
cout << "retrieve those values in priority order.\n";
while(!pq.empty()) {
cout << "Popping ";
cout << pq.top() << "\n";
pq.pop();
}
cout << endl;

return 0;
}</source>

==Instantiating an STL priority_queue: a priority queue of integers, doubles, and integers sorted using std::greater <>==

<source lang="cpp">#include <queue>
int main ()
{
using namespace std;
// A priority queue of integers sorted using std::less <> (default)
priority_queue <int> pqIntegers;
// A priority queue of doubles
priority_queue <double> pqDoubles;
// A priority queue of integers sorted using std::greater <>
priority_queue <int, deque <int>, greater <int> > pqIntegers_Inverse;
return 0;
}</source>

==priority_queue of double==

<source lang="cpp">#include <iostream>
using std::cout;
using std::endl;
#include <queue>
int main()
{
std::priority_queue< double > priorities;

priorities.push( 3.2 );
priorities.push( 9.8 );
priorities.push( 5.4 );
cout << "Popping from priorities: ";

while ( !priorities.empty() )
{
cout << priorities.top() << " ";
priorities.pop();
}
cout << endl;
return 0;
}</source>
<pre class=codeResult>Popping from priorities: 9.8 5.4 3.2</pre>

==priority_queue of int: top, pop, empty()==

<source lang="cpp">#include <queue>
#include <iostream>
using namespace std;
int main(int argc, char** argv)
{
priority_queue<int> myQueue;
myQueue.push(3);
myQueue.push(4);
myQueue.push(2);
myQueue.push(1);
while (!myQueue.empty()) {
cout << myQueue.top() << endl;
myQueue.pop();
}
return (0);
}</source>

==priority_queue of int, vector of int and greater==

<source lang="cpp">#include <queue>
#include <functional>
#include <iostream>
using namespace std;
int main(int argc, char** argv)
{
priority_queue<int, vector<int>, greater<int> > myQueue;
myQueue.push(3);
myQueue.push(4);
myQueue.push(2);
myQueue.push(1);
while (!myQueue.empty()) {
cout << myQueue.top() << endl;
myQueue.pop();
}
return (0);
}</source>

==priority_queue: pop==

<source lang="cpp">#include <iostream>
#include <queue>
using namespace std;
int main()
{
int thedata[] = {45, 34, 56, 27, 71, 50, 62};
priority_queue<int> pq;
cout << "The priority_queue size is now " << pq.size() << endl;

cout << "Pushing 4 elements " << endl;
for (int i = 0; i < 4; ++i)
pq.push(thedata[i]);
cout << "The priority_queue size is now " << pq.size() << endl;
cout << "Popping 3 elements " << endl;
for (int i = 0; i < 3; ++i) {
cout << pq.top() << endl;
pq.pop();
}
cout << "The priority_queue size is now " << pq.size() << endl;
return 0;
}</source>
<pre class=codeResult>The priority_queue size is now 0
Pushing 4 elements
The priority_queue size is now 4
Popping 3 elements
56
45
34
The priority_queue size is now 1</pre>

==priority_queue: push and size==

<source lang="cpp">#include <iostream>
#include <queue>
using namespace std;
int main()
{
int thedata[] = {45, 34, 56, 27, 71, 50, 62};
priority_queue<int> pq;
cout << "The priority_queue size is now " << pq.size() << endl;

cout << "Pushing 4 elements " << endl;
for (int i = 0; i < 4; ++i)
pq.push(thedata[i]);
cout << "The priority_queue size is now " << pq.size() << endl;
return 0;
}</source>
<pre class=codeResult>The priority_queue size is now 0
Pushing 4 elements
The priority_queue size is now 4</pre>

==priority_queue: push, pop, top, empty==

<source lang="cpp">/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <queue>
using namespace std;
int main()
{
priority_queue<float> q;
// insert three elements into the priority queue
q.push(66.6);
q.push(22.2);
q.push(44.4);
// read and print two elements
cout << q.top() << " ";
q.pop();
cout << q.top() << endl;
q.pop();
// insert three more elements
q.push(11.1);
q.push(55.5);
q.push(33.3);
// skip one element
q.pop();
// pop and print remaining elements
while (!q.empty()) {
cout << q.top() << " ";
q.pop();
}
cout << endl;
}</source>
<pre class=codeResult>66.6 44.4
33.3 22.2 11.1</pre>

==priority_queue: top==

<source lang="cpp">#include <iostream>
#include <queue>
using namespace std;
int main()
{
int thedata[] = {45, 34, 56, 27, 71, 50, 62};
priority_queue<int> pq;
cout << "The priority_queue size is now " << pq.size() << endl;

cout << "Pushing 4 elements " << endl;
for (int i = 0; i < 4; ++i)
pq.push(thedata[i]);
cout << "The priority_queue size is now " << pq.size() << endl;
cout << "Popping 3 elements " << endl;
for (int i = 0; i < 3; ++i) {
cout << pq.top() << endl;
pq.pop();
}
cout << "The priority_queue size is now " << pq.size() << endl;

cout << "Popping all elements" << endl;
while (!pq.empty()) {
cout << pq.top() << endl;
pq.pop();
}
cout << "The priority_queue size is now " << pq.size() << endl;
return 0;
}</source>
<pre class=codeResult>The priority_queue size is now 0
Pushing 4 elements
The priority_queue size is now 4
Popping 3 elements
56
45
34
The priority_queue size is now 1
Popping all elements
27
The priority_queue size is now 0</pre>

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