Просмотр исходного текста страницы C++ Tutorial/queue stack/priority queue

==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>