priority queue c++ code stl
// C++ program to demonstrate min heap
#include <iostream>
#include <queue>
using namespace std;
void showpq(priority_queue <int, vector<int>, greater<int>> gq)
{
priority_queue <int, vector<int>, greater<int>> g = gq;
while (!g.empty())
{
cout << '\t' << g.top();
g.pop();
}
cout << '\n';
}
int main ()
{
//for max heap // by default use
// priority_queue<type>name;
// for min heap//
priority_queue <int, vector<int>, greater<int>> gquiz;
gquiz.push(10);
gquiz.push(30);
gquiz.push(20);
gquiz.push(5);
gquiz.push(1);
cout << "The priority queue gquiz is : ";
showpq(gquiz);
cout << "\ngquiz.size() : " << gquiz.size();
cout << "\ngquiz.top() : " << gquiz.top();
cout << "\ngquiz.pop() : ";
gquiz.pop();
showpq(gquiz);
return 0;
}
// using GCC 10.2 (C++2a) compiler
#include <functional>
#include <queue>
#include <vector>
#include <iostream>
template<typename T> void print_queue(T& q) {
while(!q.empty()) {
std::cout << q.top() << " ";
q.pop();
}
std::cout << '\n';
}
int main() {
std::priority_queue<int> q;
for(int n : {1,8,5,6,3,4,0,9,7,2})
q.push(n);
print_queue(q);
std::priority_queue<int, std::vector<int>, std::greater<int> > q2;
for(int n : {1,8,5,6,3,4,0,9,7,2})
q2.push(n);
print_queue(q2);
// Using lambda to compare elements.
auto cmp = [](int left, int right) { return (left ^ 1) < (right ^ 1); };
std::priority_queue<int, std::vector<int>, decltype(cmp)> q3(cmp);
for(int n : {1,8,5,6,3,4,0,9,7,2})
q3.push(n);
print_queue(q3);
}
//Shubh'grepper
// Implementation of priority_queue in c++
//queue with elements in decreasing order
priority_queue<int> pq;
// queue with elements in increasing order using compare function inside declaration
priority_queue <int, vector<int>, greater<int> > pq;
//priority_queue of type pair<int, int>
#define pp pair<int, int>
priority_queue <pp, vector<pp>, greater<pp> > pq;